from Nina Tannenwald, The Nuclear Taboo:
The United States and the Nonuse of Nuclear Weapons Since 1945
(forthcoming, Cambridge University Press)
This paper, “Nuclear Weapons and the Vietnam War,” is a chapter from Nina Tannenwald’s forthcoming book The Nuclear Taboo: The United States and the Nonuse of Nuclear Weapons Since 1945 (from Cambridge University Press). The book focuses on how the U.S. president and his advisers thought about the use of nuclear weapons in times of crisis, and analyzes military, political, and normative factors that constrained resort to their use. The book argues that a nuclear taboo has developed in global politics, which has helped to delegitimate nuclear weapons as weapons of war. The analysis draws on extensive primary source material, including declassified documents and materials obtained under the Freedom of Information Act, as well as personal memoirs and interviews. The chapter on the Vietnam War is the most extensive discussion to date of the issue of nuclear weapons in the Vietnam War.
Nina Tannenwald is Joukowsky Family Research Assistant Professor at the Watson Institute for International Studies at Brown University, and is currently a Carnegie Scholar on leave at the Center for International Security and Cooperation at Stanford University. She can be contacted at 650-723-6840 or email@example.com.
Never had the military gap between a superpower and a nonnuclear
state been greater; never was it less likely to be invoked.
Henry Kissinger, 1994.
Of all cases of Cold War conflict in which the United States could have used nuclear weapons, the Vietnam War provides one of the strongest tests of a taboo against their first use. In Vietnam, the United States chose to lose a humiliating and destructive war against a small, nonnuclear adversary while all its nuclear weapons remained on the shelf. During the ten year military commitment to South Vietnam in the 1960s and 1970s, the United States sustained large losses in men, money and materiel at tremendous political cost. U.S. officials repeatedly declared that the United States could not tolerate the loss of Southeast Asia to communism, and that the war was vital for U.S. interests, prestige, and security.
As the war escalated, the United States was willing to maintain policies of great destructiveness. Operation Rolling Thunder, begun in March 1965, continued for three years and dropped more bombs on Vietnam than had been dropped on all of Europe in WWII. Starting in 1969, B-52 raids demolished vast areas in North and South Vietnam, Cambodia and Laos. U.S. forces employed herbicides and defoliants to obliterate croplands and forests, dropped flame throwers and napalm, and eventually mined Haiphong harbor. It is estimated that some 3.6 million Vietnamese, both North and South, were killed in the conflict, and 58,000 Americans.
The Vietnam War also makes a good case for exploring the role of a taboo because of a widely perceived analogy to the Korean War among U.S. decisionmakers at the time. In Korea the United States had demonstrated that, despite its virtual nuclear monopoly, a nuclear power could engage in a limited, nonnuclear war. However, because of the perceived military and political costs of that war for the United States, after Korea a great deal of debate took place as to the feasibility and desirability of fighting another such limited war in the same way. One popular lesson the Army (along with some political leaders) learned from the Korean stalemate was never again a land war in Asia, whose real meaning, administration insiders with access to military planning understood, was never again a land war against China without nuclear weapons. Doctrines of limited nuclear war developed in the mid-to-late 1950s and early 1960s elaborated the necessity of being willing and able to employ nuclear weapons in a local or regional conflict, and in something less than an all-out nuclear exchange.
Had U.S. leaders wished to use nuclear weapons in Vietnam, there was no lack of warheads nor any shortage of suitable targets. Ports, landing places, supply lines, bridges, railways and airfields could all have been hit decisively with relatively low-yield weapons. As McGeorge Bundy, national security adviser to presidents Kennedy and Johnson, later observed, such targets could have been hit with nuclear weapons quite possibly with human losses lower than those of the war that was actually fought. Further, fear of nuclear retaliation was not a prominent concern. Bundy recalled, Very little, if at all, was [the nonuse of nuclear weapons] for fear that friends of [North] Vietnam with warheads of their own, Russians or Chinese, would use some of them in reply.
Given this context, one of the remarkable features of the Vietnam War is how little serious thought U.S. leaders gave to the possibility of using nuclear weapons. Despite the commitment to avoiding defeat, the prevailing theories of limited nuclear war, and the levels of destruction wrought upon Vietnam by conventional means, U.S. political and military leaders never really came close to using nuclear weapons in the conflict. Presidents Kennedy and Johnson gave little serious consideration to nuclear options and declined to make any nuclear threats, despite some recommendations to do so. While President Nixon and his national security adviser Henry Kissinger more actively explored nuclear options, and engaged in vague nuclear threats, in the end they also did not come close to actually using such weapons in the conflict.
Still, they were not quite as much of a non-issue as Bundy portrayed in his majesterial history of nuclear decisionmaking. In reality, they were an ongoing subtext of a war that took place in a Cold War context. The possibility of employing nuclear weapons was discussed in various meetings of high-level officials before the first major American troop deployments in March 1965 and at sporadic intervals up through 1972. Both military and political leaders thought that tactical nuclear weapons would be militarily useful, and even necessary, if the conflict expanded, and U.S. leaders received recommendations to use them or threaten to use them from reputable individuals, including Bundy himself. Also, Nixon and Kissinger thought about it themselves. The possible use of tactical nuclear weapons in the war was the occasional subject of public rumor and speculation, and emerged as an issue in the presidential campaigns of 1964 and 1968.
Why did U.S. leaders not resort to use of tactical nuclear weapons to avoid a frustrating defeat and perhaps shorten the war and save American lives and treasure? Fear of uncontrolled escalation to war with Russia or China is an important part of the explanation. However, such risks were highly disputed throughout the war, and military and most key political leaders endorsed policies that involved risking war with China if necessary. Given this situation, political and normative constraints on the use of nuclear weapons became particularly salient. Ultimately, while nuclear weapons might have been militarily useful in the war, it was clear that, by the time the war was fought, they were politically unusable, and for some officials, even morally unacceptable. The constraining and constitutive effects of a taboo against first use of nuclear weapons operated powerfully for U.S. leaders during the Vietnam War, both for the majority who shared the taboo and for the minority of those who did not.
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The Johnson Administration and Vietnam
In 1961 President Kennedy had rejected intervening in the Laos crisisdefying the recommendations of most of his advisers in doing so—as soon as he realized that U.S. troops would inevitably be outnumbered on the ground and that U.S. military chiefs would count on nuclear weapons to redress the balance. The issue of nuclear weapons arose again under President Johnson in the context of the decision of 1964-65 to intervene militarily in Vietnam, which culminated in the Rolling Thunder bombing campaign and the first major introduction of U.S. troops in March 1965. Once the United States had committed troops to the defense of South Vietnam, the Joint Chiefs of Staff regularly pushed for major expansions of the war, including nuclear options. The Johnson administrations most extensive discussions of nuclear weapons took place during the 1968 siege of Khe Sanh, but even this did not get far. There were two sustained critiques of the use of tactical nuclear weapons in the conflict: Undersecretary of State George Balls famous October 1964 memo, and a recently declassified study conducted by physicist Freeman Dyson and three other scientists in 1966. Both of these papers came down strongly against the use of nuclear weapons in the war.
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Main Scenarios for Use of Nuclear Weapons
The main scenario for resort to nuclear weapons was a major ground war against Chinese and North Vietnamese troops, although other options were occasionally proposed. Both military and political leaders thought that use of tactical nuclear weapons in such a war would be likely, and possibly even required, to avoid defeat. Although military commanders were at times divided over whether nuclear weapons would be needed in a wider war, the Joint Chiefs did estimate that tactical nuclear weapons would be militarily useful, arguing in a memo in March 1964 that nuclear attacks would have a far greater probability of stopping a Chinese attack than responding with conventional weapons. As a JCS working group put it, Certainly no responsible person proposes to go about such a war [against the North Vietnamese and Chinese], if it should occur, on a basis remotely resembling Korea. Possibly even the use of nuclear weapons at some point is of course why we spend billions to have them. The Joint Chiefs essentially assumed that Eisenhower era policies remained in forcethat the United States had undertaken to defend many areas on the assumption that nuclear weapons would be used as necessary and that they would be effective.
Military leaders were unsure, for example, whether conventional bombing of Chinese supply lines in North Vietnam would be sufficient and assumed that at least ground forces, and possibly nuclear weapons, would be required. Admiral Harry D. Felt, Commander in Chief, Pacific (CINCPAC) believed that in the event of a major ground war, there was no possible way to hold off Communist forces on the ground without the use of tactical nuclear weapons, and that it was essential that U.S. commanders be given the freedom to use them as the contingency plans assumed. Chair of the Joint Chiefs General Earle Wheeler opposed using nuclear weapons to interdict supply lines but thought they would be necessary in a major war against China, and should be used only in extreme cases such as to save a force threatened with destruction or to knock out a special target like a nuclear weapons facility. However, General Maxwell Taylor, who had served as chairman of the Joint Chiefs and for a while as U.S. ambassador to South Vietnam, was more doubtful about the need for nuclear weapons.
Top political leaders did go as far as the Joint Chiefs. But during their deliberations in 1964-65 over whether to intervene in the war, they raised the issue of nuclear weapons, and seemed prepared to accept that they must be ready for their use. The U.S. Ambassador to South Vietnam, Henry Cabot Lodge, during meetings in April and May 1964, raised the question of whether nuclear weapons would be needed to defend South Vietnam. In a meeting on April 27, Secretary of State Dean Rusk expressed concern about whether this would bring the Soviets in, and also noted that he had been much struck by Chiang Kai-Sheks strongly expressed opposition to the use of nuclear weapons. William Bundy, Assistant Secretary of State for the Far East, suggested that limited use of such weapons for interdiction, in unpopulated areas, might be a different story. Rusk appeared doubtful that this could be effective, although he allowed that some sort of threats might be useful. 
In November 1964, shortly after Johnson was reelected president, an interagency task force chaired by William Bundy was formed to analyze major courses of action for the United States in Vietnam. In written comments on the draft papers laying out three options, A, B and C, Bundy asked with regard to Option B, the most aggressive course of action, At what stage, if ever, might nuclear weapons be required, and on what scale? What would be the implications of such use? He commented, This is clearly a sensitive issue. The President may want a more precise answer than appears in the papers.
On November 23, the JCS, in a memo to Secretary of Defense Robert McNamara, criticized option A as inadequate, and offered their own versions of options B and C which would include an advance decision to continue military pressures, if necessary, to the full limits of what military actions can contribute toward U.S. national objectives. In the context, the reference to nuclear weapons was unmistakable. The Chiefs had argued earlier, on November 10, that the risk of nuclear conflict should deter Chinese communist intervention, while expressing a clear willingness to use nuclear weapons should the Chinese intervene.
During the meeting of the Executive Committee (ExCom) of the NSC on November 24 to discuss the three options, someone asked whether nuclear weapons might be used. McNamara said he could not imagine a case where they would be considered, but McGeorge Bundy thought that under certain circumstances there might be political and military pressure to consider their use. However, no precise answer was forthcoming, and the Pentagon Papers narrative notes after one such inconclusive mention of nuclear weapons that again, the point was not really followed up. The ExCom eventually chose option C, the Chiefs plan, with some modifications. The final December 2 draft of the paper (approved by Johnson on December 7) incorporated the Chiefs call for aggressive countermoves to North Vietnamese escalation, but emphasized troop deployments and did not incorporate the JCS language committing the United States to the full range of military actions.
While no nuclear weapons were deployed in Vietnam, they were on board aircraft carriers and stockpiled in the region, increasing in numbers up through mid-1967. CINCPAC plans for a major escalation of the war included both nuclear and nonnuclear options. Recently declassified Pacific Command histories confirm the existence of these nuclear war plans, first revealed in the Pentagon Papers. A U.S. response to Chinese intervention into hostilities would require implementation of CINCPAC OPLAN 39-65 and/or OPLAN 32-64. In the event of Chinese entry into the war, Strategic Air Command (SAC) forces would strike selected targets within China using nuclear and/or nonnuclear weapons, as directed by the JCS. Additionally, when American Marines arrived in Da Nang in March 1965, they brought eight-inch howitzers that were nuclear-capable, though they did not have nuclear warheads. It would thus have been relatively easy for the United States to change the character of the war to a nuclear one.
There were several constraints on using nuclear weapons, however, including the risk of escalation, political costs, and moral considerations.
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Uncertain Escalation Risks
The most significant material constraint on using nuclear weapons was the risk of a wider war with China. U.S. leaders worried that a U.S. invasion of North Vietnam or the use of tactical nuclear weapons there could bring China into the war. Winning a war against China might itself require use of nuclear weapons. In a remote but worst-case scenario, this could provoke Soviet entry into the war, although most U.S. officials judged this unlikely. Thus the United States might be forced to use nuclear weapons first, with unpredictable, and possibly disastrous, consequences.
However, political and military leaders disagreed bitterly over such escalation risks throughout the war. The JCS tended to see them as much lower than did political leaders, and hence were more willing to endorse aggressive policies. The Chiefs, along with commanders in the field, consistently lobbied for expanding the war and removing limitations on the fighting as the only way to achieve victory. On January 22, 1964, they told McNamara that the United States must be prepared to put aside many of the self-imposed restrictions which now limit our effectiveness, and to undertake bolder actions which may embody greater risks. They advocated a vigorous bombing campaign against North Vietnam and the introduction of U.S. combat forces in both North and South Vietnam. In response, McNamara directed them to plan a campaign of covert actions and air and sea attacks on North Vietnam up to but not including nuclear weapons. The JCS then complained that if China entered the war nuclear weapons might be needed, and submitted a plan culminating in a strike at the Chinese atomic production facility that would produce a bomb in October 1964. McNamara took a similar aggressive stance on this initially, but then scaled it back before presenting it to the President.
Former president Eisenhower, called in for a consultation on Vietnam in February 1965, shortly before the final decision supporting the first major deployment of American troops, found the nuclear option entirely reasonable. He told President Johnson and senior advisers that he thought the Chinese would not enter the war, but if they did he would use any weapons required, including nuclear weapons if necessary. He recommended using carrier-based tactical nuclear weapons for instant retaliation, suggesting that they could be used on large troop formations and supply depots. In his view, this would not increase the chances of escalation. Emphasizing the utility of deterrent threats, he recommended threatening China with nuclear weapons.
Further, as he had done in the Korean War, he explicitly advocated challenging the taboo on the first use of nuclear weapons. The United States, he said, should not be bound by the restrictions of the Korean War, including the gentlemans agreement on not using nuclear weapons. This would keep the Chinese out of the war. This view was shared by South Vietnamese leader General Nguyen Khanh, who had told Rusk during Rusks visit to southeast Asia in April 1964 that as far as he was concerned the United States could use anything it wanted against China. Eager to expand the war to the North, Khanh had no objections to use of nuclear weapons, noting on another occasion that decisive use of atomic bombs on Japan had saved not only American but also Japanese lives.
Eisenhowers statements suggest that he, like the JCS, perceived few material constraints on the use of nuclear weaponshe believed that nuclear weapons would be useful on the battlefield, saw minimal escalation risks, and demonstrated no evident concern about long term consequences of their use. He uttered no cautionary words of any kind to Johnson and his advisers. In his view, the main constraint on use of nuclear weapons was a political-normative onethe gentlemans agreementwhich he advocated breaking. It might be argued that he was an aging general no longer in the loop, but his statements are entirely consistent with those he made when he was president. 
Secretary of State Rusk endorsed Eisenhowers recommendations to institute a campaign of pressure against North Vietnam, although he did not share Eisenhowers views on nuclear weapons. In a strong personal memo to the President shortly after the meeting with Eisenhower, he wrote, Everything possible should be done to throw back the Hanoi-Viet Cong aggressioneven at the risk of major escalation. At an NSC meeting in May 1964, Rusk had suggested moving a U.S. division in Korea to Southeast Asia, and making a public declaration that any attack on South Korea would be met by the use of nuclear weapons. He believed that if escalation brought about a major Chinese attack, it would also involve use of nuclear arms, a risk he was willing to take. But like the military, Rusk thought the escalation risks were low. He thought that the Chinese leaders were practical men who would act prudently, in part because of the U.S. nuclear arsenal. As he noted to the Romanian foreign minister in October 1965, After all, Chinese nuclear capability within the foreseeable future will always be trivial as compared to that of the U.S. Nevertheless, Rusk vigorously opposed bombing near the Chinese border, and, although he found some use for nuclear threats, unlike Eisenhower, did not actually advocate use of nuclear weapons.
The militarys benign views of the escalation risks were especially alarming to Undersecretary of State George Ball, who worried about a protracted ground war with China, which might produce substantial U.S. casualties. As he wrote in a famous skeptical memo on U.S. conduct of the war to McNamara, Bundy, and Rusk in October 1964, At this point, we should certainly expect mounting pressure for the use of at least tactical nuclear weapons. The American people would not again accept the frustrations and anxieties that resulted from our abstention from nuclear combat in Korea. Ball worried that the fact that there was no longer any shortage of suitable nuclear warheads removed an important material constraint on their
use. The rationalization of a departure from the self-denying ordinance of Korea would be that we did not have battlefield nuclear weapons in 1950yet we do have them today. Given a situation of nuclear plenitude, and the militarys benign assessment of the consequences of a wider war or using nuclear weapons, Ball worried that there were few military or material constraints on the militarys analysis of nuclear options.
Ball and others sensitive to escalation risks also worried about the uncertain Soviet reaction to a U.S. use of nuclear weapons. He wrote in his October 1964 memo, While one cannot be certain, the best judgment is that the Soviet Union could not sit by and let nuclear weapons be used against China. Similarly, in a lengthy memo to Johnson on the same day as the meeting with Eisenhower, Vice President Hubert Humphrey, who opposed the 1965 decision to expand the war, cautioned that if a war with China had been ruled out in 1952-53 when only the United States had a usable nuclear capability, it would be even harder to justify such a war now. No one really believes the Soviet Union would allow us to destroy Communist China with nuclear weapons, as Russias status as a world power would be undermined if she did. At the Honolulu conference on June 2, 1964, Rusk had also noted the risk of provoking a nuclear exchange with the Soviets, with all that this involved.
Nevertheless, unlike in previous Cold War crises, during the Vietnam conflict U.S. military leaders did not think war with the Soviet Union was imminent, and were not deterred in their conduct of the war by fear of Soviet entry into the hostilities. This was due to the Sino-Soviet split and the highly public animosity between the two communist great powers by the mid-1960s, along with the relative detente between the United States and the Soviet Union in the wake of the 1962 Cuban missile crisis. Official U.S. intelligence estimates consistently stated that it was unlikely either China or the Soviet Union would intervene unless the United States invaded North Vietnam with a massive show of troops, bombed China, or attacked Soviet supply ships in Haiphong harbor. A Special National Intelligence Estimate of October 9, 1964 stated that We are almost certain that both Hanoi and Peiping are anxious not to become involved in the kind of war in which the great weight of US weaponry could be brought to bear against them. Even if Hanoi and Peiping estimated that the US would not use nuclear weapons against them, they could not be sure of this….
By mid-1965 the administration was convinced that the Soviet Unions commitment to long-term improvement of relations with the West took precedence over its support for North Vietnam. In spring 1965, after operation Rolling Thunder had begun, Chinese leader Zhou Enlai signaled to Washington through the Pakistanis and the British that Chinese forces would not become involved militarily in Vietnam if the United States refrained from invading North Vietnam or China and did not bomb the Norths Red River dikes. However, should war break out, even nuclear weapons would not force them to quit, and the war would have no boundaries.
However, President Johnson was determined, even obsessed, with keeping the war restrained, a view shared by McNamara and others, who thought that even if the actual risks of a wider war were low, the consequences were unacceptable. The problem was the risk of uncontrolled escalation, which could lead to possibly catastrophic outcomes. Johnson and his advisers, veterans of the 1962 Cuban missile crisis, were committed to limiting as much as possible the geographical area of the conflict and the volume of force used. Johnson, in particular, was haunted by the ceaseless fear of Soviet and Chinese intervention.
Still, although escalation concerns played a role, they were far from determining. While national leaders clearly wanted to avoid escalation that might lead to a large conventional or nuclear war, top political and military officials disagreed strongly over the risks and consequences of escalation. In practice, the fear of defeat in Vietnam repeatedly made significant risks of escalation acceptable. On February 9, 1965, McGeorge Bundy wrote Senator Mike Mansfield that the administration was willing to run the risk of war with China, and implied a willingness to make a sacrifice at least equal to that of the Korean War. Although top civilian leaders did not advocate or support use of nuclear weapons, and although McNamara later remembered himself appalled by the JCS position on nuclear weapons, at times during 1964-65, comments by him and other civilian leaders showed a willingness to run risks that might have led to nuclear war against China, much as the Chiefs were advocating.
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Political and Normative Concerns
In the face of uncertainty and disagreement over escalation risks, political and normative concerns about using nuclear weapons may have become particularly salient, if not decisive, for many top officials. As in Korea, U.S. leaders worried that, given world public abhorrence of nuclear weaponsnow even stronger than in the 1950sthe use of such weapons in the Vietnam conflict would jeopardize the U.S. moral and leadership position in the eyes of friends and allies, especially if the United States used them again on Asians. In a memo to President Johnson, Undersecretary Ball wrote: To use nuclear weapons against the Chinese would obviously raise the most profound political problems. Not only would their use generate probably irresistable pressures for a major Soviet involvement, but the United States would be vulnerable to the charge that it was willing to use nuclear weapons against non-whites only.
Indeed, foreign leaders privately and publicly cautioned against use of nuclear weapons. Chiang Kai Shek, leader of nationalist China, told Rusk during Rusks trip to southeast Asia in April 1964 that he was opposed in principle to use of nuclear weapons, particularly in settling the China problem. Returning to Washington, Rusk reported to the NSC that he had been impressed by Chiangs passionate statement that nuclear war in Asia would be wrong. Chiangs opposition to use of nuclear weapons undoubtedly stemmed in part from his concern that Taiwan would be the most likely object of a Chinese counterattack, probably overwhelming, and Chiang and his regime would be at risk. A month later, in Honolulu, Rusk noted that many free world leaders would oppose this [use of nuclear weapons]. When the French ambassador to Washington suggested to Rusk in July 1964 that a nuclear threat might have a most sobering effect on the Chinese, Rusk again responded that Asians, including even Chiang Kai Shek, were strongly opposed to use of nuclear weapons in Asia. Other foreign leaders urging restraint including U Thant, Secretary-General of the UN, Prime Minister Lester Pearson of Canada, and British prime minister Harold Wilson. Mounting public opposition to the war gave U.S. leaders a demoralizing foretaste of the kind of world public outrage that a use of nuclear weapons might provoke.
But it was not only the concerns and abhorrence of others that played a role. A nuclear taboo was becoming entrenched among high officials of the Kennedy and Johnson administrations. President Johnson, especially, was obsessed with limiting the war. Like Truman during the Korean War, he abhorred the thought that he might ever have to consider use of nuclear weapons. His memoirs make no mention of nuclear weapons being considered in Vietnam. His senior advisers have testified strongly that by as early as 1964 Johnson was clear in his own mind that he would not order a first use of nuclear weapons except perhaps in the case of overwhelming Soviet aggression in Europe. He never raised with these advisers the question of how far the American people would support a decision to use the bomb in Vietnam.
Johnson had spoken out strongly during the 1964 presidential campaign when Senator Barry Goldwater, campaigning for the Republican presidential nomination in May 1964, suggested in a speech that tactical nuclear weapons should be treated more like conventional weapons, and that they should be used in Vietnam. The previous October, Goldwater had recommended delegating responsibility for decisions on use of nuclear weapons to military commanders in the field under some circumstances (Johnson, continuing Eisenhower policies, had delegated some authority but only under very limited circumstances). In a speech in Detroit on Labor Day, 1964, Johnson came out strongly against Goldwaters views. He described the catastrophe of nuclear war and said, Make no mistake. There is no such thing as a conventional nuclear weapon. He continued:
For 19 peril-filled years no nation has loosed the atom against another. To do so now is a political decision of the highest order. And it would lead us down an uncertain path of blows and counterblows whose outcome none may know. No President of the United States can divest himself of the responsibility for such a decision. 
The reference to 19 peril-filled years is a strong one, and Johnsons statement emphasizes both the tradition of nonuse and the fear of uncontrollable escalation. Bundy wrote later that although there was politics in Johnsons speech, there was passionate conviction as well. Two factors appeared to be key in Johnsons thinking: the long term effect of any use of the bomb on the survival of mana prudential consideration, and the desire not to be the first president in twenty years to use nuclear weapons, that is, to break the powerful tradition of nonuse that had now developeda taboo consideration. Johnson did not want to be the president who set the precedent for use of nuclear weapons. For him, it appears, the use of the bomb in Vietnam was quite literally unthinkable.
Many of Johnsons advisersespecially Robert McNamara and Dean Ruskalready possessed a set of strongly held beliefs about nuclear weapons by this point in time. Cold War crises over Berlin and Laos (1961) and Soviet missiles in Cuba (1962) had already forced them to confront the possibility of using nuclear weapons. Appalled by the Eisenhower nuclear doctrine of massive retaliation, Kennedy and his advisers had sought more flexible war plans that included greater emphasis on conventional weapons. Further, in the early 1960s, an emerging debate among the fledgling group of civilian arms control analysts on the merits of a no first use policy began to challenge the logic of the prevailing U.S. deterrence policy based on the threat to use nuclear weapons first.
Under McNamara the Pentagon began to revise Eisenhowers Basic National Security Policy (BNSP), but the process bogged down in several dilemmas, one of which was the puzzling question of when, if at all, tactical nuclear weapons might be used. It was one of several reasons why there was never a final agreed BNSP for the Kennedy administration. Walt Rostow, a hawk who took over the process of revising the plan when he became head of Policy Planning in the State Department in 1962, found the role of tactical nuclear weapons a tough nut to crack. It remained an unresolved dilemma because of differences of view in the Pentagon. Thus the draft BNSP was simply left with a statement of the dilemma posed by tactical nuclear weapons: they were extremely important as a deterrent against massive conventional attack in Europe and elsewhere, but their actual use could produce civil and human destruction on a vast scale, in some cases (depending on locale) tantamount to the strategic use of nuclear weapons.
The growing opposition to the policy of use of tactical nuclear weapons significantly reflected McNamaras personal views. From early in his tenure as secretary of defense, McNamara opposed use of nuclear weapons, viewing them as morally objectionable and lacking in utility, issues he often ran together. He had been horrified by the briefing he received in early February 1961, only two weeks in office, from General Thomas Power, commander of the Strategic Air Command (SAC), on SIOP-62, the U.S. plan for nuclear war inherited from the Eisenhower administration. It called for an all-out preemptive first strike on the Soviet Union, Eastern Europe and China, involving a million times as much explosive power as used in Hiroshima, in response to an actual or merely impending invasion of Europe by the Soviet Union that involved no nuclear weapons at all. Millions of Chinese would be destroyed for no obvious reason. Returning to Washington, McNamara ordered a review of the nuclear stockpile, which eventually resulted in a unilateral 50% cut in stockpile megatonnage. He also ordered an increase in nonnuclear capabilities for countering conventional aggression so that the United States would not be forced to rely on tactical nuclear weapons.
McNamara apparently decided very early on that the United States should never strike first with nuclear weapons. This was made clear in policy documents he sent to the JCS chairman shortly after the war plan briefing that so disturbed him. He has stated frequently that he privately advised both Kennedy and Johnson never to initiate the use of nuclear weapons, and they agreed.
Daniel Ellsberg, a Pentagon planner who disagreed with McNamaras strong advocacy of bombing North Vietnam, and who later became famous for leaking the Pentagon Papers to the press, nevertheless felt that McNamara shared his strong personal abhorrence of nuclear weapons. Recalling a private meeting with McNamara in 1961 in which McNamara spoke with great passion about the dangers of nuclear weapons and U.S. nuclear war plans, Ellsberg wrote that he impressed me strongly and positively that day with his conviction that under no circumstances must there be a first use of U.S. nuclear weapons in Europe. He added, Ive never had a stronger sense in another person of a kindred awareness of this situation and of the intensity of his concern to change it. After the meeting, McNamaras assistant told Ellsberg that Johnsons thinking on this subject was not one iota different from McNamaras.  This meeting took place even before the 1962 Cuban missile crisis, an event which drove home to McNamara the dangers of uncontrolled escalation.
Like McNamara, Dean Rusk, Secretary of State to both Kennedy and Johnson, found nuclear weapons abhorrent. With a background in international law, he took a strongly principled approach to diplomacy and Americas role in the world. George Ball, who disagreed with Rusks fairly aggressive views on the war, nevertheless described him as a man of extraordinary integrity and selflessness. According to Rusk, we never seriously considered using nuclear weapons in Vietnam. He advocated aggressive uses of force but opposed use of nuclear weapons in Vietnam and elsewhere because of fallout risks, political costs, lack of good targets in Vietnam, adequate conventional alternatives, but especially because of the unacceptable killing of civilians. It is clear that Rusk had been impressed by the opposition to use of nuclear weapons he had encountered during his trips to Asia. He noted that many Asians seemed to see an element of racial discrimination in use of nuclear arms. Was it something the United States would do to Asians but not to Westerners? He wrote later, Under no circumstances would I have participated in an order to launch a [nuclear] first strike, with the possible exception of a massive [Soviet] conventional attack on West Europe,” which he thought unlikely. The only rational purpose of nuclear weapons is to ensure that no one else will use them against us.
These are remarkable admissions from McNamara and Rusk. In effect, top U.S. officials harbored private commitments to no first use, in part for moral reasons, despite the fact that such views directly contradicted official U.S. deterrence policy relying on a threat to initiate use of nuclear weapons. (They also contradicted U.S. plans for limited war emphasizing first use of nuclear weapons in a conflict with large Chinese forces in Asia). McGeorge Bundy wrote later that he believed that McNamara and Rusk would have resigned if President Johnson had asked for a decision to use the bomb in Vietnam, and that Johnson quietly appreciated this.
The 1964 Ball Memo
The most systematic analysis of the consequences of using nuclear weapons in Vietnam came from Undersecretary Ball in his October 1964 memo. While he again raised the risk of Soviet intervention following any use of nuclear weapons, his primary emphasis was on the negative political consequences of any such use. The entire passage under the heading Pressure for Use of Atomic Weapons, more than a dozen paragraphs, is devoted to assessing the political costs to U.S. leadership of any use of the bomb. Nowhere here does he mention either risks of nuclear retaliation or escalation to a wider war, nor the military utility of nuclear weapons, which he appears to assume (by contrast, when he does mention the risk of Soviet intervention in response to a U.S. use of nuclear weapons, it is in one sentence in the subsequent section on Possibility of Soviet Intervention).
In his analysis, Ball noted the lack of meaningful distinction between tactical and strategic weapons in the eyes of the public, and the profound shock that would follow any use of nuclear weapons not merely in Japan but also among the nonwhite nations on every continent. He predicted that our loss of prestige in the non-aligned and less-developed countries would be enormously magnified if we were led to use even one nuclear weapon.
Most significant, however, was an analysis of the consequences of legitimizing use of nuclear weapons. Ball wrote that if the United States used such weapons,
…our action would liberate the Soviet Union from the inhibitions that world sentiment has imposed on it. It would upset the fragile balance of terror on which much of the world has come to depend for the maintenance of peace. Whether or not the Soviet Union actually used nuclear weapons against other nations, the very fact that we had provided a justification for their use would create a new wave of fear….The Communists would certainly point out that we were the only nation that had ever employed nuclear weapons in anger. And the Soviet Union would emphasize its position of relative virtue in having a nuclear arsenal which it had never used.
The consequences of this could not be overstated, he wrote. The first use of the bomb by the United States would set back all the progress made in superpower relations over the previous few years. It would also generate domestic resentment against a Government that had gotten America in a position where we had again been forced to use nuclear power to our own world discredit.
Balls concern about the negative precedent set by the use of even a single nuclear weapon was not primarily because it would demonstrate that such weapons were militarily useful, or that it would invite Soviet retaliation. Rather, it would suggest that nuclear weapons were legitimate. If the U.S. resorted to the bomb, the Soviet Union would then feel free to use it against other nations. Legitimizing the use of nuclear weapons would undermine a major normative inhibition on resorting to them in wara major stabilizing factor of successful nuclear deterrence (the balance of terror). In other words, a shared normative expectation of nonuse was an essential element of, not an alternative to, stable nuclear deterrence. Because of this, the country that broke the tradition of nonuse of nuclear weapons would be stigmatized as a pariah among nations.
Balls memo—or at least parts of it—was not well-received. Rusk and McNamara entirely rejected his questioning of the administrations arguments for conventional bombing of North Vietnam. However, it is likely that they were quite sympathetic to his arguments about nuclear weapons, which accorded substantially with their own views.
Still, there is some evidence that U.S. officials were not totally averse to making nuclear threats. On April 22, 1965, just after the first deployment of US troops to Vietnam, and as the Johnson administration was shifting its focus to a greater effort to win the ground war, McNamara gave a not-for-attribution briefing to reporters. After reviewing and defending U.S. strategy in Vietnam, he introduced a new elementa nuclear bluff. A New York Times reporter recorded his words:
We are NOT following a strategy that recognizes any sanctuary or any weapons restriction. But we would use nuclear weapons only after fully applying non-nuclear arsenal. In other words, if 100 planes couldnt take out a target, we wouldnt necessarily go to nuclear weapons; we would try 200 planes, and so on. But inhibitions on using nuclear weapons are NOT overwhelming. Conceded it would be a gigantic step. Quote: Wed use whatever weapons we felt necessary to achieve our objective, recognizing that one must offset against the price—and the price includes all psychological, propaganda factors, etc. Also fallout on innocents. Inconceivable under current circumstances that nuclear would provide a net gain against the terrific price that would be paid. NOT inconceivable that the price would be paid in some future circumstances McNamara refuses to predict.
These remarks created a flap when they appeared in the newspapers on April 25, and McNamara amended his comments publicly the next day. There is no military requirement for nuclear weapons in the present and foreseeable situation, he said, and no useful purpose can be served by speculation on remote contingencies. Yet, as David Kaiser notes, his original threat could not have been accidental.
While Eisenhower remained the most steadfast advocate of the utility of nuclear threats, even McGeorge Bundy toyed with the idea. In a memo to McNamara in June 1965 criticizing a vast increase in American troops that McNamara was planning, Bundy noted Eisenhowers nuclear threats in the Korean War and suggested that the United States should at least consider what realistic threat of larger action is available to us for communication to Hanoi. He added, A full interdiction of supplies to North Vietnam by air and sea is a possible candidate for such an ultimatum. These are weapons which may be more useful to us if we do not have to use them. McNamara wrote later that he did not share Bundys views on nuclear weapons and threatening their use, though he did on everything elsea recollection that is somewhat inconsistent with his behavior at the time. On December 2, 1965, McNamara referred in a telephone conversation with Johnson to certain very dangerous alternatives that we cant even put in writing around here, [and] certainly dont want to talk to anyone else about.
The nuclear bluff may have been what Bundy suggested—a strategy of communicating seriousness to Hanoi and Moscow. Soviet leaders indeed got word that U.S. officials were entertaining nuclear options, a prospect they viewed with the greatest alarm. According to historian Ilya Gaiduk, drawing on newly available Soviet documents, in summer 1965 Soviet leaders received regular reports that the United States might resort to nuclear weapons to suppress the insurgency in South Vietnam. In June 1965, Soviet intelligence informed the Kremlin that in a conversation with Italian Foreign Minister Amintore Fanfani, Rusk had admitted that the prospect of using tactical nuclear weapons in Vietnam was on the agenda of American policymakers. Although it is unclear how reliable the reporting was, or what exactly on the agenda meant, the report apparently spurred Soviet leaders to consider seriously the question of U.S. readiness to wage a nuclear war and the Johnson administrations intentions in this regard. There thus appears to have been some pattern of nuclear threatmaking, even if it was a bluff.
The nuclear bluffs notwithstanding, it became increasingly clear that, in contrast to Korea ten years earlier, use of nuclear weapons in Vietnam was indeed increasingly unthinkable.The operation of a nuclear taboo was visible in variety of ways.Political leaders rebuffed in outrage overt attempts to erode the taboo, and resisted even analyzing nuclear options.Such developments reflected a mounting burden of proof for any use of such weapons.
Not only were top officials privately opposed to use of nuclear weapons, butconsistent with taboo thinkingeven the mere analysis of such weapons in the de rigueur cost-benefit fashion for which the Kennedy administration was famous was essentially taboo. Samuel Cohen, a weapons physicist at the RAND Corporation who had advocated use of tactical nuclear weapons in the Korean War, and who was one of the rare enthusiasts for such an option in the Vietnam War, ran up against the taboo mindset. As he recalled, anyone in the Pentagon who was caught thinking seriously of using nuclear weapons in this conflict would find his neck in the wringer in short order. His formerly good relationship with Pentagon officials had plummeted because of his pro-nuclear weapons views: When the Kennedy guys came in, my relationship with the Office of the Secretary of Defense dropped off to approximately zero. Those in key positions….had no use for my views.
In Pentagon war games, such as one held in September 1964, to determine whether conventional firepower alone would stop a Chinese intervention in a war in Southeast Asia, the answer the game produced was probably not. However, only a minority of the war games American leadership voted to use nuclear weapons to destroy Chinese nuclear production facilities and execute a general nuclear attack on China.
One overt challenge to the taboo was the earlier-mentioned attempt by Goldwater during the 1964 presidential campaign to reintroduce the notion of conventional nuclear weaponsthe same notion that Eisenhower and Dulles had sought unsuccessfully to promote ten years earlier. In May 1964, Goldwater argued publicly that nuclear weapons should have been used at Dien Bien Phu to defoliate trees, and that, in similar fashion, low-yield atomic weapons should be used as defoliants along South Vietnams borders, along with an expanded conventional bombing campaign of North Vietnam. The idea drew an immediate blast from UN Secretary-General U Thant. The Johnson administration went after Goldwater with devastating effect, running anti-Goldwater TV adds with antinuclear themes. The Pentagon responded to Goldwaters folly by describing technical characteristics of nuclear weapons, arguing that it was absurd to call them conventional weapons. Goldwater persisted that the army possessed very small nuclear weapons with a fraction-of-a-kiloton blast. But to no avail. Johnson responded with his famous Labor Day speech that there is no such thing as a conventional nuclear weapon. McNamara wrote later of Goldwater, His statement implied that he saw no real difference between conventional weapons and nuclear weapons. He went so far as to suggest the president should instruct commanders in Vietnam to use any weapons in our arsenal. I profoundly disagreed and said so.
Goldwaters statements endorsing the legitimacy of nuclear weapons—like those of Eisenhower and Dulles earlier—represented a public attempt to challenge the growing taboo on their use by eroding the line between conventional and nuclear weapons. The strong government and public reaction illustrated how anathema such a view was to most people. The Johnson administration used to the controversy to political advantage, tapping into the publics fear of nuclear war. But its strong response also served to reinforce and uphold the by-this time widely shared public sentiment that nuclear weapons were not conventional weapons, and to reaffirm the taboo. Goldwaters comments contributed significantly to his landslide defeat. By the mid-1960s, advocating use of nuclear weapons in a campaign speech was beyond the bounds of acceptability for most people.
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Investigating and Challenging the Taboo
As in Korea, those who disagreed with official policy thought that normative concerns inhibited policymakers from thinking rationally about nuclear options. Samuel Cohen, the RAND weapons scientist, attempted in vain to interest Washington in the virtues of discriminate nuclear weapons in Vietnam. He recalled, I put my mind to work on how nuclear weapons might be used to thwart the Vietcong. His account of his efforts to promote tactical nuclear options during the war, as well as his analysis of policymakers and scientists resistance to this option, provide a fascinating window into the operation of the taboo.
As he recalled later, during a presentation on tactical nuclear weapons he gave to key planners in the State Department in 1965, it quickly became evident that however intrigued his audience was from a technical point of view, they were adamantly opposed to the development and use of such weapons from a political point of view. During the course of the talk he described several hypothetical weapon systems in which low-yield nuclear weapons would be used to propel metal projectiles or massive conventional weapons payloads. In one example, the nuclear explosion would take place over the battlefield but would give only conventional effects on the target. He expected that there might be some interest in these options, which he argued were more effective and discriminating than standard high explosive attacks. Instead, the opposition remained unanimous, for the simple reason that it was not really the nature of the effects that counted. Rather, it was the fact that a nuclear explosion was taking place over the area of theater operations.
Intrigued with the anti-nuclear sentiment, Cohen now attempted to discern how deep it was. He described another hypothetical device, a giant nuclear explosive cannon where very low-yield explosives could shoot massive conventional payloads over many hundreds of miles. The military effects of the weaponpurely conventionalwould be felt only on the battlefield, while the source of energynuclearrequired to deliver these weapons would be well outside the battlefield zone. His audience remained adamantly opposed and unanimous that this scheme was also unacceptable, even if the nuclear explosions took place in the United States. These reactions impressed upon Cohen the depth of official feeling against the military use of nuclear explosives. By now I realized that as long as a nuclear explosive was used in anger, U.S. policy held the type of explosive and geographical location of detonation to be absolutely irrelevant. The cardinal point was that it was the act of detonating the explosive in anger that was a political taboo.
Cohens fictitious weapons amounted to an explicitand ingeniousdevice for exploring the scope and content of the taboo, which he did not personally share. Indeed, the word unthinkable increasingly crept into discourse on nuclear weapons. In a memo of September 12, 1967 to Walt Rostow, who had replaced McGeorge Bundy as national security adviser, Robert Ginsburgh, Rostows deputy, listed seven military measures to achieve a more spectacular rate of progress in the war. The last was Create wasteland with low yield nuclear weapons in southern part of North Vietnamvirtually unthinkable.
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The War Escalates
Both the Joint Chiefs and General William Westmoreland, the American commander in Vietnam, pressed for a more ambitious bombing program throughout 1966 and into 1967. They lobbied for major escalation of the war and more troops in 1966, after the much-criticized Christmas 1965 bombing pause, and again in late May 1967. In a memo to McNamara on May 20, 1967, the Chiefs argued for increased air attacks on North Vietnam, and stated their belief that invasions of North Vietnam, Laos, and Cambodia might become necessary, involving the deployment of U.S. forces to Thailand, mobilization of reserves, and, quite possibly, the use of nuclear weapons in southern China. They recognized that these actions could lead to confrontation with China and/or the Soviet Union in Southeast Asia or elsewhere, but they considered such steps necessary to shorten what they predicted would otherwise be five more years of war. McNamara later described that he was appalled by the cavalier way in which the military recommended aggressive policies, which in his view raised unacceptable risks of war with China including possible U.S. use of nuclear weapons.
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The 1966 Jason Report
The only known systematic study of the role of tactical nuclear weapons in the war was conducted by four civilian scientists consulting for the U.S. government as part of the JASONs—a group of some forty young scientists who had met each summer since 1959 to consider defense-related problems for the Pentagon. As the war escalated in the spring of 1966, a high-ranking Pentagon official with access to President Johnson was heard by a scientist to say, It might be a good idea to toss in a nuke from time to time, just to keep the other side guessing. Freeman Dyson, one of the authors of the report and a physicist at Princeton, recalled that this happened at a briefing at the State Department or at an informal party, while Steven Weinberg, another of the scientists, then on leave from Berkeley at Harvard, recalled a rumor circulating that someone in the Pentagon or National Security Council was pushing for the use of tactical nuclear weapons in Vietnam or Laos. These two—-along with Robert Gomer and S. Courtenay Wright, both at Chicago at the time—were so appalled by this statement they decided something must be done.
Worried that nuclear weapons were not unthinkable enough, the scientists obtained permission from the Defense Department to carry out a systematic study of the likely consequences of using tactical nuclear weapons in Vietnam. They explicitly intended it to put a definitive end to any lingering thoughts that such weapons might be useful in the war. Whereas Balls 1964 memo had emphasized political consequences, this study focused on the military utility of nuclear weapons in the conflict.
The group who took on this task was not responding to specific nuclear war plans or threats, nor to a request from the Pentagon. Dyson wrote later that he had no evidence that the use of nuclear weapons was considered seriously in prosecuting the Vietnam War. But, he added, We had no way to tell whether the speaker was joking or serious. Just in case he was serious, we decided to do our study.
I, and I believe others as well, Weinberg wrote later, felt that the use of nuclear weapons would make the war even more destructive than it had already become; it would create a terrible precedent for the use of nuclear weapons for something other than deterrence; it wouldnt help much with the war; and it would open up the possibility of nuclear attacks on our own bases in Vietnam. All this was an immediate reaction, not based on any careful analysis. So we decided to do the analysis and write a report.
After three man-months of work, the authors produced a highly-classified report titled Tactical Nuclear Weapons in South-East Asia, which presented their analysis and conclusions in what Dyson later described as a deliberate hard-boiled military style. The analysis sought to demonstrate that even from the narrowest military point of view, disregarding all political and ethical considerations, the use of nuclear weapons would be a disastrous mistake.
Recently declassified, the 55-page report makes a strong case against the utility of tactical nuclear weapons in Vietnam. The analysis focused on whether there would be suitable targets in Vietnam for the tactical use of nuclear weapons, and on the effects on enemy ground operations. It defined tactical use in the strict sensethat is, on military targets, only within the theater of ground combat, and while avoiding civilian casualties so far as practicable. The reason for this focus, the authors explained, is that we wish to stay as much as possible in the realm of technical military analysis and to avoid involvement with political and moral judgments.
The analysis highlighted numerous military obstacles to the tactical use of nuclear weapons: the difficulty of target acquisition, and the fact that even when good targets existed, use of tactical nuclear weapons would not substantially affect enemy operations. In some cases, there were more effective alternatives.
The report identified numerous targets against which, in principal, tactical nuclear weapons would be useful. Bridges, airfields, and missile sites make good TNW [tactical nuclear weapons] targets. Airfields were also ideal targets for TNW and are expensive targets for conventional bombing. The introduction of tactical nuclear bombing would quickly render the ten remaining operational airfields in North Vietnam inoperable. Other potential targets were large troop concentrations, tunnel systems, and Viet Cong bases in South Vietnam. TNW can be very effective if the position of bases are known accurately, especially if attacks can be delivered without warning. Still, using tactical nuclear weapons in South Vietnam would be “helpful, but in no sense decisive. It would be equivalent to a major increase in the strength of B-52 bombardments.” 
For instance, it would take 3000 tactical nuclear weapons per year to interdict supply routes like the Ho Chi Minh trail. More problematically, U.S. forces might become vulnerable to a Soviet-orchestrated counterattack; and that first use of tactical nuclear weapons against guerillas might set a precedent that would lead to use of similar weapons by guerillas against more vulnerable U.S. targets.
In reality, the report concluded, few suitable targets or effective uses could be found. The use of TNW on troop targets would be effective only in stopping the enemy from moving large masses of men in concentrated formations. So long as the enemy moves men in small groups and uses forest cover, he would offer few suitable troop targets for TNW. Using bomblet-canister ordnance would be more cost-effective than using nuclear weapons on troops in the open. Viet Cong base areas in South Vietnam could be effectively destroyed with tactical nuclear strikes, but this would require large numbers of weapons and an accurate location of targets by ground patrols. Tactical nuclear weapons could also block roads and trails in forested areas by blowing down trees, but fallen trees could be relatively easily cut through and cleared.
Finally, using fallout from groundburst weapons to make trails impassable would require repeated use of nuclear weapons and would not by itself provide a long-lasting barrier to the movement of men and supplies, without endangering civilian populations at up to a distance of 200 miles. In conducting their analysis, the authors drew in part on findings from RAND and Research Analysis Corporation nuclear war-gaming studies from the late 1950s and early 1960s, as well as the 1965 OREGON TRAIL studies, which revealed the difficulties of timely troop target acquisition.
The second half of the report considered the vulnerability of U.S. forces to attack by insurgents armed with tactical nuclear weapons supplied by the Soviet Union or China. U.S. bases, harbors and staging areas in South Vietnam were vulnerable to Soviet bombers and infiltration by guerillas, and would offer attractive targets for [the retaliatory use of] TNW. In fact, they were far more vulnerable to the effective use of nuclear weapons than were the smaller, relatively mobile, and difficult-to-find enemy encampments.
In addition, the authors emphasized the tremendous long-range importance of avoiding setting a precedent for the use of TNW by guerilla forces. U.S. forces, they wrote, would always be much more vulnerable than insurgents to nuclear attack. The dangers posed by increased guerilla activity around the world in the future will certainly become more acute if the U.S. leads the way by initiation of tactical nuclear war in Southeast Asia.
The report came to a strong conclusion: the overall result of our study is to confirm the generally held opinion that the use of TNW in Southeast Asia would offer the U.S. no decisive military advantage if the use remained unilateral, and it would have strongly adverse military effects if the enemy were able to use TNW in reply.
Although the study stated at the outset that it was intended be a purely technical analysis, in fact it included strong judgments about the political costs and consequences of using nuclear weapons. The last section, Political Consequences, listed possible scenarios in which the response to a U.S. use of tactical nuclear weapons was escalation, although it did not estimate the relative probabilities of these scenarios. The ultimate outcome is impossible to predict, the authors noted. We merely point out that general war could result, even from the least provocative use of NW that either side can devise.
Most significantly, they concluded that even if massive retaliation did not result, U.S. first use of tactical nuclear weapons in Vietnam would have many serious long-range consequences:
The most important of these is probably the crossing of the nuclear threshold. As Herman Kahn points out, abstention from the use of any NW is universally recognized as a political and psychological threshold, however rational or irrational the distinction between nuclear and nonnuclear may be. Crossing it may greatly weaken the barriers to proliferation and general use of nuclear weapons. This would be to the ultimate disadvantage of the U.S., even if it did not increase the probability of strategic war.
Whether or not the Vietnamese National Liberation Front or its external allies countered with use of nuclear weapons of their own, the authors argued, the effect of a U.S. nuclear first use on world opinion in general and on U.S. allies in particular would be extremely unfavorable. With the exception of Thailand and Laos, the reaction would almost certainly be condemned even in Asia and might result in the abrogation of treaty obligations by Japan. The effect on public opinion in the United States would be extremely divisive, no matter how much preparation preceded it. In sum, they concluded, the political effects of U.S. first use of TNW in Vietnam would be uniformly bad and could be catastrophic.
From a purely military perspective, therefore, even if the target acquisition problem could be solved (and that was not evident), for tactical nuclear weapons to be effective they would have to be used in such large quantities (and with such great frequency) that political costs would outweigh military benefits. When the risk of retaliation was added in, along with the risk of the weapons spreading to guerilla forces around the world, it amounted to a strong argument against the use of tactical nuclear weapons in the war.
The report is curious in some respects. It focuses on scenarios that were already at the time widely regarded as unlikely, such as the use of nuclear weapons against insurgents. The Soviet supply of tactical nuclear weapons (the report mentioned atomic mortars or recoilless rifles) to North Vietnamese forces was also an unlikely scenario, given how tightly the Soviet Union controlled its nuclear weapons. Further, the report pays no attention to what was actually in the U.S. nuclear war plans for Southeast Asia in the mid-1960s. These puzzling features can perhaps be explained by the circumstances which motivated the scientists to undertake the study (and the Defense Department to agree to it), discussed further below.
A final interesting aspect of the study is the way the four scientists, who personally found nuclear weapons morally objectionable, took pains to couch their argument against use of nuclear weapons in purely military terms, believing that this would enhance its reception with military planners and decisionmakers in the Pentagon and CIA, its most likely audience. As Weinberg later described, using nuclear weapons in Vietnam seemed like a terrible idea for a host of ethical and moral, but also possibly political reasons. He explained further that Although my objections were ethical and political, I also thought it was likely one could make a good case from a purely hard-boiled military view, but I didnt know. He thus participated in the study with some expectation that this would be the case. The authors themselves viewed the report as offering a powerful critique of the utility of nuclear weapons in the war. That paper gives all the reasons why you wouldnt use nuclear weapons in Vietnam, observed one of its authors in a later interview.
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Did the Study Have Any Effect?
The fate of this report, and its role, if any, in influencing the administrations thinking on the role of nuclear weapons in the war, remains vague. The authors handed it to their sponsors in the Defense Department, never to hear of it again. However, Seymour Deitchman, at the time at the Institute for Defense Analyses (IDA), a federally funded research center under contract to the Defense Department, and acknowledged in the report, wrote later that the report went to McNamaras office. IDA provided administrative and technical support for the JASON group. Deitchman recalled briefings on the JASON studies of that summer to three audiences: the JASONs themselves, John McNaughtonthen Assistant Secretary of Defense for International Security Affairs, who managed the JASON relationship with McNamara, and McNamara himself.
Deitchman recalled clearly the nuclear weapons study briefing to the JASONs. I remember being struck by the main conclusion, that if we started down that route [using nuclear weapons] we risked being hurt much more than the North Vietnamese and the Viet Cong… McNamara received briefings on the JASON studies every year, and, according to Deitchman, was likely briefed in late August or early September 1966. This probably included a briefing on the nuclear weapons study, although Deitchman did not remember for sure. According to Deitchman, after the briefings, the report was never circulated.
Since the Defense Department had to sign off on the topics for the JASON studies (which were chosen by the JASONs themselves), why would it agree to a study on tactical nuclear weapons in Vietnam? Here we have only faint but intriguing outlines. Deitchman recalled recurring talk around the Pentagon that spring and summer about using tactical nuclear weapons to block passes between North Vietnam and Laos, especially the Mu Gia Pass, a key part of the supply route heading south. The pass was heavily and unsuccessfully bombing by B-52s starting in July 1966, with heavy losses for the United States. Thus when the JASONs proposed the nuclear weapons study topic, McNaughton and McNamara might have found it a useful device for showing what a bad idea using nuclear weapons would be.
It thus remains unclear what effect the report had. It is likely that it had little or no influence on McNamara himselfbecause he was already adamantly opposed to use of nuclear weapons. By that point in time (1967), he was also increasingly skeptical that the war could be won by deploying more troops to South Vietnam and intensifying the bombing of North Vietnam (he offered his resignation to Johnson in November of that year, largely over disillusionment with the war). In a later interview, McNamara did not remember the study or the briefing, but conceded that the briefing could have happened. He said that he himself would have had no need for such a study, since he and his assistant McNaughton were already totally opposed to nuclear weapons, but that did not mean it wasnt useful.
It might have, for example, helped him put an end to loose talk about nuclear options. When Deitchman returned to the Pentagon in the fall of 1966, he heard no further talk of using nuclear weapons in Vietnam. Although I dont know, he recalled, I think it is reasonable to conclude from that that, if consideration had been given to the idea before the study, Mr. McNamara simply dismissed it as something not to think about seriously, and therefore the talk simply went away.
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The one attempt by the Johnson administration to look more closely at the military utility of nuclear weaponsto relieve the siege of the Marine garrison at Khe Sanh in early 1968aborted quickly in a public relations nightmare. This was perhaps the moment of gravest risk of the kind anticipated by the JASONs. New evidence suggests that top administration officials discussed the topic at several meetings throughout the tense key days of late January and early February 1968, albeit with a tone of the greatest reluctance. Johnson made clear he had no wish to face a decision on use of nuclear weapons and repeatedly sought assurance from military leaders that they had adequate conventional forces to defend Khe Sanh.
In a memo to General Wheeler on January 31, 1968, Robert Ginsburgh, Walt Rostows deputy on the National Security Council and its liaison to the JCS, noted that if a desperate situation developed at Khe Sanh, where 6000 Marines were besieged by 15,000-20,000 North Vietnamese troops, the issue of TAC NUCS will be raised. Ginsburgh asked Wheeler whether contingency target analysis would be in order. Handwritten on the memo were notations that plans should be very very very closely held. Ginsburgh and Rostow had apparently already been discussing the issue for a week or so.
The next day Wheeler solicited the views of General Westmoreland and Admiral Ulysses Sharp, American commanders in Vietnam, on whether nuclear weapons should be used if the situation became desperate. Noting the perceived parallels between Khe Sanh and Dien Bien Phu, he asked whether there were suitable targets for nuclear strikes, whether some contingency planning might be in order, and what you consider to be some of the more significant pros and cons. He cautioned them to hold this subject very closely. Westmoreland and Sharp had apparently already been discussing the need for some planning on the issue, and had already instituted it under the strictest need to know basis, Sharp wrote back the next day. All three military leaders thought the use of nuclear weapons an unlikely eventuality but felt military prudence alone required some such planning.
As requested, Westmoreland began to convene a secret study group to analyze nuclear options. But almost immediately Washington quashed it, fearingtoo latethat it would leak to the press. Johnsons political advisers reversed course, moving rapidly to forestall any request for a nuclear option from the JSC by making sure Westmoreland had all the conventional forces he needed to defend Khe Sanh. Rostow suggested in a memo to the president on February 2 that Westmoreland be offered an extra reserve division, explaining his desire to avoid a situation of battlefield crisis in which Westy and the JCS would ask you to release tactical nuclear weapons. He also urged that General Wheeler be informed that it was his duty to minimize the likelihood that the Chiefs would raise the nuclear issue.
In a memo the next day General Wheeler sought to reassure the president, writing that the use of nuclear weapons should not be required in the present situation. But he did not rule them out. Should the situation in the DMZ area change dramatically, we should be prepared to introduce weapons of greater effectiveness against massed forces. Under such circumstances I visualize that either tactical nuclear weapons or chemical agents would be active candidates for employment. In a memo to Johnson the same day, apparently spurred by suggestions in the press and other parts of the government that high-level considerations of nuclear weapons were under way, Rostow apologized for his blunder in raising the issue with General Wheeler and the commanders, which inadvertently created the impression that the government was thinking about using nuclear weapons. He explained that it was never his intent that any formal staff work be done on the nuclear issue, adding that the fault, therefore, is mine.
In other words, not only should nuclear weapons not be used, nuclear options should not even be studied. No analysis should be permitted, nor even the appearance of it. The taboo qualities emerge sharply heresomething that is not done, not said, not analyzed, not thought about. Not even Walt Rostow should be permitted to analyze the issue. Johnson was later furious about the irresponsibility with respect to our planning to use nuclear weapons.
Westmoreland, a consistent advocate of greater force in Vietnam, wrote in his memoirs that he thought consideration of tactical nuclear options at Khe Sanh a prudent idea. The region around Khe Sanh was virtually uninhabited so civilian casualties would be minimal. He saw analogies to the use of atomic bombs in WWII to send a message to Japan, as well as to the role of U.S. nuclear threats to North Korea which many thought had ended the Korean war. He wrote that use of a few small tactical nuclear weapons in Vietnamor even the threat of themmight have quickly brought the war there to an end. If Washington officials were so intent on sending a message to Hanoi, surely small tactical nuclear weapons would do this effectively. Westmoreland felt at the time and even more strongly later that failure to consider the nuclear alternative was a mistake.
Despite the administrations efforts, rumors that it was contemplating the use of tactical nuclear weapons in Vietnam swirled nonetheless, and the resulting popular outcry illustrated the extreme sensitivity of the issue. When Senator Eugene McCarthy, campaigning for president, aired the matter publicly a few days later, the White House and Pentagon vehemently denied that nuclear weapons were under consideration.  General Wheeler told a Senate subcommittee that he did not think nuclear weapons were needed for Khe Sanhs defense, but if it developed that they were, the JCS would recommend to President Johnson that they be used. On February 9, testifying before the Senate Foreign Relations Committee, Rusk denied the existence of any plans for use, or of stockpiles, of nuclear weapons in Vietnam, but failed to rule it out entirely. Senator Fulbright, chairman of Committee, along with Senators Clark and Aiken, denounced the possibility of use of nuclear weapons. The Congressional inquiry was prompted in part by speculations about the reasons for sending four nuclear scientists to Vietnam. The scientists were in fact being sent to study the McNamara linean electronic barrier to prevent North Vietnamese infiltration across the demilitarized zone separating the two Vietnams. Their trip had nothing to do with nuclear weapons. British Prime Minister Harold Wilson, on a visit to Washington during this debate, said bluntly during an interview on CBSs Face the Nation that it would be sheer lunacy for the United States to use tactical nuclear weapons. It would not only be disastrous to Americas position, he said, but it would also run a very, very great risk of escalation for the world.
However, a few public figures called for use of nuclear weapons. Representative Wayne Hays a member of the House Foreign Affairs Committee, disagreed with the critics, saying, Rather than suffer a disastrous defeat and the annihilation of a considerable number of our forces, I think we would just be foolish and completely stupid if we got in that (Khe Sanh) position and did not use them. Congressman Charles Bennett called for whatever forces are needed to win the war including even the threat or use of atomic weapons and the invasion of North Vietnam if necessary.
In a press statement on February 9 and again during a press conference a week later, President Johnson denied strongly that he had received any request from his military or political advisers to use nuclear weapons in Vietnam. He emphasized that any decision to use nuclear weapons rested with the President. In his seven years in the Executive Branch, he said, no recommendation has been made to me about deployment of nuclear weapons. Beyond that, I think that we ought to put an end to the discussion. Press Secretary George Christian made clear that the Johnson administration was upset that the nuclear weapons question had been raised at all. Irresponsible discussion and speculation are a disservice to the country… he stated.
Johnsons categorical denial was probably somewhat overstated, since the nuclear weapons issue had been discussed at the regular Tuesday luncheon at the White House among the secretaries of defense and state, the president and General Wheeler. It was true that the president had not received any requests for use of nuclear weapons. However, he had not received definite assurances from the JCS that they would never make such a request; the military chiefs were not able to give Johnson the categorical assurance that Khe Sanh could be held without nuclear weapons, under bad weather conditions that hindered conventional air support.
After prominent scientists George Killian, George Kistiakowsky and I.I. Rabi expressed concern in a telegram to Eisenhower about the possible use of nuclear weapons in Vietnam, McNamara called each of them personally to assure them that there was no consideration of use of nuclear weapons. They had been inspired to write in part by a newspaper report in which Eisenhower was reported to have left the door open for use of nuclear weapons in South Vietnam. Although Eisenhower was no longer president, his record as a distinguished general gave his views on military issues some weight.
Overall, during the Khe Sanh crisis, political leaders displayed much greater concern, and spent much more time dealing with, the public relations dimension of nuclear weapons than their actual utility at Khe Sanh. As a Washington Post article put it, Pentagon weapons experts contended the technical problems were almost as large as the political problems in using nuclear weapons. In other words, political constraints posed an even greater obstacle to the freedom to use nuclear weapons than their technical difficultiesin this case, primarily radioactive fallout. On March 9, the Washington Post editorialized that use of nuclear weapons in Vietnam would be a disaster. When Johnson administration officials met with the Wise Mena group of former high officials consulting on U.S. military options in Vietnama month later, on March 25, to make decisions on the failing war effort in the wake of the Tet offensive, the nuclear lesson of Khe Sanh was likely reflected. Rejecting a new troop request of 200,000, they also concluded, with no evident discussion, that use of atomic weapons is unthinkable.
The administration did ensure that Westmoreland had sufficient conventional forces to defend Khe Sanh. The battle that took place there was, in Westmorelands words, an awesome display of firepower; given the bomb-delivery capacity of the B-52s, one of the heaviest and most concentrated in the history of warfare. B-52s eventually dropped more than 100,000 tons of explosives on a five-square-mile battlefield. At Westmorelands request, Johnson did permit the use at Khe Sanh of so-called controlled fragmentation munitions (COFRAM), shells and grenades, some containing submunitions, that exploded with very lethal effects. Information on the existence and use of this weapon was guarded as closely as possible.
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Even in the face of the growing number of American casualties in Vietnam, public opinion remained opposed to use of nuclear weapons in the war. U.S. public opinion had consistently been against the first use of nuclear weapons since the mid-1950s. The moderate amount of polling on the topic during the Vietnam War showed that, in terms of public opinion, the taboo against first use held during the war, even while American casualties mounted.
In the first stages of the war (1964-66), there was only limited support for using nuclear weaponsabout 15% approved taking such a step. As the war continued, support for using nuclear weapons increased to 24 percent and then to 42 percent. But on a question asked both before and after the winter 1968 Tet offensive about the use of atomic ground weapons, a Harris poll found the answer the same in both cases: about 25 percent in favor, 55 percent opposed. When the question was worded more aggressivelywhether respondents would agree or disagree with the view that we should go all-out to win a military victory in Vietnam, using atomic bombs and weapons, some 26 percent approved and, higher than on the Harris ground weapon question, about 65 percent disapproved.
Thus attitudes in support of using nuclear weapons in Vietnam never reached a plurality or majority. Not only did the public largely reject using nuclear weapons, but toward the end of the war a survey of elite leaders indicated they rejected it also. Further, as Thomas Graham has reported, a more diverse base of survey questions showed that the taboo applied not only to Vietnam, but to other proposed uses of nuclear weapons as well, suggesting the more general nature of the sentiment. This pattern of public attitudes (low support at first, then higher, but only under certain limited conditions) fits the same general pattern found in the Korean War, although the magnitudes differ. The American public was less willing to recommend the use of atomic weapons in Vietnam than in Korea.
At a retrospective conference on the Vietnam War in 1997, McNamara denied forcefully that world public opinion constrained U.S. use of nuclear weapons in Vietnam. He insisted instead that it was because it was neither militarily desirable nor morally acceptable…. It had nothing whatever to do with what the world might have thought about it. He continued, …Presidents Kennedy and Johnson made clear and concrete, unqualified decisions not to use nuclear weaponsparticularly because it was considered morally unacceptable. That was also my recommendation to them. I was with each of them, on separate occasions, when they made these decisions. The use of nuclear weapons in Vietnam was never considered viable.
Given the significant role that negative public opinion played in shaping American decisionmaking on the war more generally, McNamaras strong claim might seem implausible. However, his views on nuclear weapons were shaped well before U.S. intervention in Vietnamthrough his experiences of crises over Berlin, Laos and Cuba. His statement underscores the degree to which he and others believed that using nuclear weapons was simply wrong; i.e. that it was not a matter of appeasing others views, rather WE thought it was wrong.
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Nixon and Kissinger
In stark contrast, the taboo operated primarily as an instrumental, rather than substantive, constraint on the top officials of the Nixon administration, who exhibited no such personal reluctance to thinking about nuclear options. President Nixon, the archetypal anti-communist hawk, dreamed of ending the Vietnam war with a knockout blow. He believed approvingly that U.S. nuclear threats had ended the Korean war, and expected to utilize the same principle of the threat of excessive use of force to bring victory in Vietnam. Describing his madman theory to longtime aide H.R. Haldeman in fall 1968, he would convince North Vietnamese leaders that he was obsessed with winning the war and willing to unleash the most ruthless violence against their country if they did not end it, implying a nuclear threat.
Nixon was a strong advocate of U.S. nuclear superiority and, like Eisenhower, whom he had served as vice president, a believer in the efficacy of nuclear threats. Although he believed a nuclear war with the Soviet Union would be a disaster, he does not appear to have viewed nuclear weapons themselves with any particular moral compunctions. In every Cold War crisis, Nixon had always urged escalation and greater use of force. As Vice President in 1954 under Eisenhower, he had supported the deployment of U.S. troops to replace French losses in Vietnam and the following year had advocated that the United States use atomic weapons to halt Chinese moves into Vietnam. In 1964 he had urged retaliatory strikes against Laos and North Vietnam. The following year he opposed the Johnson administrations efforts to start negotiations on the ground that the North Vietnamese would regard it as evidence of weakness. He had opposed constant calls for negotiation since those would only encourage Hanoi. During the 1968 presidential campaign, he attacked the Johnson administration for its policy of gradualism in the use of force. He often told aides in the early days of his administration, I dont intend to be the first president to lose a war.
Nixon, who prided himself on being tough, stated in an interview with Time magazine in 1985 that he had considered the use of nuclear weapons four times during his administration, one of which was to end the Vietnam War. He told Time that he had rejected the bombing of dikes, which would have drowned 1 million people, for the same reason that I rejected the nuclear option. Because the targets presented were not military targets.
However, Henry Kissinger, Nixons national security adviser, repudiated Nixons claim publicly. Kissinger reported in an interview that “I can safely say that there was never a concrete occasion or crisis in which the use of nuclear weapons was considered by the government.” He added, None of these crises reached a point where there was any planning to use nuclear weapons. There was never any decisioneven contingent decisionto use nuclear weapons if such a contingency should arise. And there was never any discussion of how far we would be prepared to go in these contingencies.
These statements, and the record on Nixons and Kissingers attitudes toward the use of nuclear weapons more generally, are difficult to interpret. Because of Nixons penchant for hyperbole and inflated rhetoric, and because key memoir accounts of this period are unusually ideological and selective, the evidence often appears contradictory. Some of the Vietnam files of Nixons and Kissingers papers have recently been opened to the public, but a full account must await a future telling. According to Stephen Ambrose, a leading Nixon biographer, in Nixon’s considerations of how to end the war, use of atomic weapons “on the model of Japan in WWII” was “out of the question.” However, it does not seem to have been entirely out of the question, and especially not for Kissinger, whose denial appears overstated with respect to the case of Vietnam.
During the review process of Vietnam even before his inauguration, Nixon says he considered andwith apparent regretrejected either bombing dikes or using nuclear weapons, saying he could not allow my heart to rule my headhis heart wanting the knockout blow, his head constrained by the public outrage he knew it would provoke. Had he chosen either of these courses of action, he acknowledged, the resulting domestic and international uproar would have damaged our foreign policy on all fronts. He also noted it would have hampered improved relations with the Soviet Union and China. His reasoning was instrumental, and he never ruled out use of nuclear weapons in general.
Earlier, during both the 1964 and 1968 presidential campaigns, Nixon had come out against use of nuclear weapons in Vietnam. In August 1964, Nixon had written a Readers Digest article, Needed in Vietnam: The Will to Win, in which he had put only one limit on what should be done in Vietnam: I am firmly opposed to the use of nuclear devices of any sort, not only because of the disastrous effect this would have on world opinion, but because it is wholly unnecessary. In late January 1965 he advocated U.S. naval and air bombardment of North Vietnam, while saying that ground forces would not be necessary and reiterating that nuclear weapons should not be considered. Four years later, running again for president, Nixon got a great break when, in October 1968, presidential candidate George Wallace announced that he had chosen General Curtis LeMay, former head of the strategic nuclear bombing command, as his running mate. LeMay, in his first press conference, said that he would use nuclear weapons immediately in Vietnam. Nixon said he “disagreed completely” and accused Wallaces American Independent Party of irresponsible and excessively hawkish attitudes on foreign affairs. Wallace went down to defeat, with 13.5 percent of the popular vote. Nixons public opposition during his campaigns to use of nuclear weapons in Vietnam appeared to be dictated largely by the instrumental needs of the campaign, since, according to his own account, once he gained the presidency, the nuclear option was one of the first things he thought about.
Nixons interest in exploring nuclear options as president was matched, and perhaps even exceeded, by that of his National Security Adviser Henry Kissinger. Kissinger, in his former life as an academic, had written a bestselling book, Nuclear Weapons and Foreign Policy, which advocated use of tactical nuclear weapons in limited wars. Increasingly critical of nuclear strategies based on massive retaliation, he argued that strategies of limited war and limited nuclear war would be more useful for both warfighting and diplomacy. Since the publication of the book in 1957, Kissinger had drawn back from aspects of that policy, but he continued be a strong advocate of the development of limited nuclear options. In a March 1976 interview in U.S. News and World Report, Kissinger admitted publicly that, although nonnuclear means of responding to aggression was preferable, he would not exclude the use of nuclear weapons in certain limited situations.
At his instigation, one of the first goals of the Nixon White House was to revise U.S. nuclear strategy to provide for more limited nuclear options. The day after Nixons inauguration on January 20, 1969, Nixon and Kissinger had ordered NSSM-3 (National Security Study Memorandum), a study of the conventional and nuclear balance of forces. Completed in May, it emphasized the need for limited nuclear options, a view with which Kissinger was highly sympathetic. The first week in office, the JCS had presented to Nixon and Kissinger a deeply pessimistic briefing on the Soviet nuclear arms build-up. The Soviet Union was approaching parity with the United States in nuclear forces and might even achieve superiority. For Kissinger, the impending loss of U.S. strategic superiority required a rethinking of U.S. nuclear strategy. The threat of nuclear use needed to be more plausible than simply threatening all-out war.
NSSM-3 led to a follow-on study in June 1969 requesting the NSC and the Pentagon to examine limited nuclear targeting options. Kissinger wanted the NSC staff to develop a strategy in which the nuclear options actually seemed usable. But by the spring of 1970, the administration had to put the strategic review on the back burner. Despite pressure from Kissinger, the NSC staff moved slowly on the study, in part because the development of limited nuclear options seemed a low priority in the face of other more pressing matters such as the Vietnam War and the upcoming SALT negotiations. But, increasingly, the White House encountered opposition from State Department officials who worried that the ready availability of plausible nuclear options would make recourse to the use of nuclear weapons much more likely. They also feared it would generate demands from the military for more weapons systems, and arms control supporters worried that the development of limited options would torpedo the SALT negotiations.
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Vietnam Contingency Planning
During this same period, planning began on more aggressive options for Vietnam. On January 27, 1969, Nixon, Kissinger, General Wheeler, and Secretary of Defense Melvin Laird met to discuss military options which might jar the North Vietnamese into being more forthcoming at the Paris talks. On February 21, Laird forwarded to Kissinger a very preliminary JSC report on the matter. The top secret report identified five fairly aggressive scenarios, the last one involving what it referred to as technical escalation,—use of atomic, biological or lethal chemical weapons. In evaluating this option, the report noted that use of such weapons in Vietnam would excite very strong public and Congressional reaction, adding that the predictable reaction worldwide [to this scenario], particularly in Japan and Okinawa….militate against its employment.
Neither Laird, Kissinger, nor Kissingers military assistant Alexander Haig were favorably disposed toward the proposals. In transmitting the report to Kissinger, Haig commented that the plans were more extensive than the type you and the President visualized as acceptable signals of US intent to escalate military options in Vietnam. Kissinger found the plans well conceived but that the realities of the current domestic and international environment did not lend themselves to accepting at this time the risks they laid out. He suggested more subtle actions which might have reduced risks of news media recognition or domestic turbulence, such as increased military communications and increased aerial reconnaissance, activities which might create the impression of a U.S. force build-up.
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Operation Duck Hook
Shortly, however, Kissinger chose to look into the less subtle options. During the same period that the NSC was being tasked to study limited nuclear options, Kissinger was investigating nuclear contingencies with respect to Vietnam. The key case is operation Duck Hook, a plan for a massive use of force against North Vietnam developed in the spring and summer of 1969. Developed by Kissinger and a few associates, it called for massive bombing of Hanoi, Haiphong, and other key areas in North Vietnam; the mining of harbors and rivers; the bombing of the Red River dike system; a ground invasion of North Vietnam; the blockading of Sihanoukville, the destructionpossibly with nuclear weaponsof the main north-south passes along the Ho Chi Minh Trail; and the bombing of North Vietnams main railroad links with China. A separate, even more secret study dealt with the implications of using tactical nuclear weapons on the rail lines, the main funnel for supplies from the Soviet Union and China. According to Haldeman, Nixons chief of staff and confidante, Kissinger had lobbied for nuclear options in the spring and fall of 1969.
In late August, Nixon reviewed Ks contingency plan for Vietnam but did not make a decision one way or another. In late August and into September, Kissinger feared that Nixons mental resolve for a resolute stance on the war was wavering, and he took steps to urge him to approve what was being referred to as the November Optiona savage, decisive blow against North Vietnam to end the war. On September 9, Kissinger met with General Wheeler to discuss military planning for the Duck Hook operation…and to convey to him the presidents personal mandate that planning be held in strictly military channels, which would thereby preclude discussing the plan even with the secretary of defense.
In late August or early September, Kissinger assembled a select group of his staff to undertake a top-secret study to explore the military side of the cointhat is, the existing Duck Hook studies. He described it to them as a very, very sensitive matter. In White House Years, Kissinger wrote that he told the group that what was needed was a military plan designed for maximum impact on the enemys military capability in order to force a rapid conclusion to the war. These options might include the use of a tactical nuclear weapon in a single, carefully controlled situation. A top secret Concept of Operations document of mid-September stated U.S. resolve to apply whatever force necessary to achieve basic U.S. objectives in Southeast Asia. International and domestic pressures, and the possibility of Soviet or Chinese reaction would be important factors but will not necessarily rule out bold or imaginative actions….  The document did note that bombing the dikes would raise particular problems in the United States.
Kissinger told the group, I refuse to believe that a little fourth-rate power like North Vietnam doesnt have a breaking point. The Johnson administration could never come to grips with this problem. We intend to come to grips. When one staff member asked about the possible use of nuclear weapons, Kissinger replied that it was the policy of this administration not to use nuclear weapons. But he did not exclude the use of a nuclear device to block a key railroad pass to China if that should prove the only way of doing it. One participant recalled later that I guess we were all in a sort of a mild state of shock. The emphasis of the scenarios was on delivering savage air blows, to be repeated at intervals. The study was conducted only on the basis of military effectiveness. Few moral or political considerations entered the picture. According to an NSC aide, The whole exercise struck me as being very cool and amoral, not judging it in terms of the loss of life or in terms of the escalation of the war, but simply in terms of effectiveness.
It remains unclear whether the special group ever actually considered in its study the possible use of a nuclear device as part of its proposed blockade of North Vietnam. Tad Szulc reports that it did not, and that Kissinger is not known to have alluded to it again. Kissinger aide Roger Morris said that he had been shown nuclear targeting plans, while other aides later told interviewers that they did not recall encountering any evidence that Nixon and Kissinger considered using a nuclear device in the Duck Hook operation. Haldeman apparently opposed use of nuclear weapons in Vietnam primarily because it might hurt Nixons reelection chances in 1972.
During September and October, Nixon continued his threats of dramatic escalation of the war. To bolster them, he ordered a secret worldwide nuclear alert, one of the largest secret military operations in U.S. history. It began October 13 and lasted a month. However, as massive public protests against the war scheduled for October 15 and November 13-15 in the United States loomed, Nixon cancelled Duck Hook. In his memoirs, he suggests that the world-wide furor over escalation of the war undermined his plans. An NSC staffer remembered it differently, recalling that the attack plans were narrowly defeated mainly because of Nixons uncertainty about military efficiency, not because of any larger doubts rooted in concern for domestic or foreign consequences. Kissinger had backed away from the plan, persuaded in part by lengthy memos from NSC aides opposing the escalation plans, in particular a scathing and detailed critique of the military operation by Lawrence Lynn, a former Pentagon official then on the NSC staff, arguing that the blockade would not work.
Suppose Nixon been able to secretly use tactical nuclear weapons in Vietnam along the lines of the secret bombing of Cambodia? There is little reason to think he would not have done so. On May 11, 1969, Nixon, Kissinger and other aides were on board a top secret Airborne Command post jet returning to Washington from Key Biscayne. Nixon read a report on nuclear operations plans which had been completed a few days earlier. One of the studys findings was that the SIOP contained no flexible limited options in its massive strike scenarios. Nixon had scribbled a few notes on yellow pad, now declassified: These plans are a disgrace. They really have no options outside these in last, because if you use the force separately the SIOP becomes impossible. If in doubt we bomb Cambodia. Does this suggest they were thinking about nuclear contingency plans for North Vietnam? It is unclear.
As it was, Nixon kept the Duck Hook planning secret from even his secretaries of state and defense, William Rogers and Melvin Laird. When they found out about itonly when Nixon himself leaked the planthey urged against it, emphasizing the mounting public opposition to escalating the war. Two scientists who were consulted on the Duck Hook nuclear targeting plans opposed the nuclear course of action, for both military and moral reasons.
With the notable exception of the maverick Samuel Cohen, most scientists and civilian defense analysts involved in policy advising opposed use of nuclear weapons in Vietnam, for both military and moral reasons. Daniel Ellsberg, at the time a defense analyst at RAND, directed a comprehensive study of U.S. military options in Vietnam requested by Kissinger in late 1968. Ellsberg adamantly refused to consider tactical nuclear options in the study. I wouldnt be party to a paper that suggested in any way that nuclear weapons deserved any consideration in Vietnam, he recalled later. The two scientists who had been asked to review the Duck Hook nuclear target folders in 1969 were distressed at the nuclear option, one of them worrying that use of nuclear weapons might bring in the Chinese. They urged Paul Doty, a leading Harvard biochemist and a friend of Kissingers, to discourage the planning, and conveyed the same views to Haldeman, an old acquaintance of one of the scientists. Even physicist Edward Teller, one of the nations most hawkish scientists, and a longstanding proponent of nuclear arms, opposed using nuclear weapons in Vietnam on the grounds that they would not be useful against guerillas. Branding those who advocated use as idiots, he proclaimed that, Only a few idiotsand they were really idiotssuggested using nuclear weapons in Vietnam. Kissinger, however, did not have much use for scientists, especially because scientists on the Presidents Science Advisory Committee did not give him the advice he wanted on ABMs. They appear to have had little impact on his thinking about nuclear weapons.
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Spring 1972: In Final Pursuit of the Knock-Out Blow
In the spring of 1972, Nixon was considering escalation options in North Vietnam that would go far beyond an all-out bombing attack. According to recently released White House tapes, on April 25, a few weeks before he ordered a major escalation of the war, Kissinger presented him with a series of escalation options, including attacking North Vietnamese power plants and docks. Haldeman and press secretary Ron Ziegler were also present. Nixon said, I still think we ought to take the dikes out now. Will that drown people? Kissinger responded, About 200,000 people. Nixon stated, No, no, no…Id rather use the nuclear bomb. Have you got that, Henry? Kissinger replied, That, I think, would just be too much. Nixon responded, The nuclear bomb, does that bother you?… I just want you to think big, Henry, for Christssake.
According to Haldemans diary, Nixon, Kissinger and Haig again discussed the possible use of nuclear weapons a week later, on May 2, as peace negotiations became intractable. The topic arose during a meeting on the presidential yacht Sequoia, shortly after Kissingers return from the Paris negotiations, in the context of a discussion of military options to end the war. Nixon rejected the nuclear option, as well as an invasion of the North and the bombing of Red River dikes. He favored instead the blockading of North Vietnamese ports and the expansion of bombing north of the 20th parallel, commenting that he wanted that place bombed to smithereens.
On May 4, discussing his decision with Kissinger, Haig and John Connally, Nixon thumped on his desk as he railed …South Vietnam may lose. But the United States cannot lose…Whatever happens to South Vietnam, we are going to cream North Vietnam…..For once, weve got to use the maximum power of this country…against this shit-ass little country…. The next day during a conversation Nixon observed to Kissinger that civilian casualties are a result of all wars. The only place where you and I disagreeis with regard to the bombing. Youre so goddamned concerned about the civilians and I dont give a damn. I dont care. Kissinger responded, Im concerned about the civilians because I dont want the world to be mobilized against you as a butcher. We can do it without killing civilians.
Nixons suggestions to use nuclear weapons against North Vietnam, or to implement other drastic measures that would kill a lot of civilians, were clearly reflections of his frustration with the war. They were not a live option. It was clear by this point in the war—as it had really been clear all along—that use of nuclear weapons was not politically feasible, either domestically or internationally. Nixon clarified this himself in an NSC meeting on May 8, when he called for a “cold-blooded analysis” of the current situation in Vietnam. After a discussion of mining options, Nixon explained, “Whatever we do we must always avoid saying what we’re not going to do, like nuclear weapons. I referred to them saying that I did not consider them necessary. Obviously, we are not going to use nuclear weapons but we should leave it hanging over them. We should also leave the threat of marines hanging over them….we shouldn’t give reassurance to the enemy that we are not going balls out.”
Thus Nixon, who clearly harbored few personal inhibitions about violating an array of important democratic norms during his presidency when he thought could get away with it, was powerfully constrained by the abhorrence and opposition of others. The restraint that he did display with regard to use of nuclear weapons was primarily the result of public opinon constraints. Haig, a hard-liner who had served in Vietnam and later became secretary of state, and who had helped plan Duck Hook, attributed the nonuse of nuclear weapons in Vietnam and other Cold War conflicts to normative concerns—-of others. He wrote in 1992, On the American side, the moral argument against the use of such weapons, or even the threat of their use, took on the force of religious belief. He argued against this moral perspective and worried that such inhibitions would undermine deterrence. Nevertheless, he wrote, ….the mere existence of our superior power often bailed us out of potential disaster even though we were determined, in the depths of the national soul, never to use it. Because of such moral inhibitions, he felt that no American president would resort to nuclear weapons except in the extreme case of the defense of Europe.
Referring to something as a religious belief suggests that it is held as a matter of faith and fervor, and is unsusceptible to‑‑or at least distinct from‑‑rational argument. This often characterizes a taboo.
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The tradition of nonuse of nuclear weapons held throughout the conflict in Vietnam. During the war, three U.S. administrations progressively upped the level of violence, and engaged in tremendously controversial policies, yet all drew the line at use of nuclear weapons. Despite the enormous costs and frustrations of the war, U.S. leaders avoided resort to the one thing that might have won itusing tactical nuclear weapons.
We can distinguish several different motivations for the nonuse of nuclear weapons in Vietnam: first, fear of inadvertent escalation, rooted in calculation about the risk of uncontrolled escalation, plus the potential for an infinitely catastrophic outcome—the dominant factor driving McNamara and others; second, preserving the tradition of nonuse, which Ball had emphasized; and finally, a taboo, a normative belief that using nuclear weapons would be wrong.
It thus appears that the chances the Johnson administration would have used nuclear weapons in Vietnam were nearly zero, no matter what Generals Westmoreland, Sharp or Wheeler thought. In contrast, for Nixon and Kissingeras for Eisenhower earlier, less influenced by personal moral convictionsthe taboo operated primarily as an instrumental constraint on resort to nuclear weapons. Although Nixon talked a tough line, and sent notes to the North Vietnamese threatening massive use of force if they did not agree to negotiate, in the end he and Kissinger were repeatedly rolled back from their aspirations for knockout blows by domestic and world public condemnation. They would have been unable to use nuclear weapons without provoking the greatest outcry. Nixon probably did not personally share the nuclear taboohe did not think it was wrong to use nuclear weaponsbut he was constrained because others, including members of his own bureaucracy, held it. As Kissinger later argued, Never had the military gap between a superpower and a nonnuclear state been greater; never was it less likely to be invoked.
How much did the taboo matter vis a vis deterrence in explaining the nonuse of nuclear weapons in Vietnam? Soviet and Chinese nuclear forces may have prevented any U.S. military thoughts of attacking Vietnamese sanctuaries inside China, but they did not prevent thoughts of attacking southern China with nuclear weapons in any expanded war. The degree to which the United States could escalate the fighting inside Vietnam was the most open question. Here, fear of a nuclear response by the Soviet Union or China did not operate strongly for U.S. leaders. Rather, they worried about the more likely possibility of a large-scale conventional war, its uncertain long-term political and military consequences, and the more remote possibility of its escalation to a nuclear war. Because these calculations were uncertain, if no taboo on first use of nuclear weapons existed, it is likely that military plans for their use would have been considered much more seriously given the Americanand conceivably even Vietnameselives such use could have saved.
But it would be a mistake to draw too sharp dichotomy between the force of the taboo and the force of escalation risks, because they are not entirely independent. The existence of a weapons taboo helps to shape judgments of what constitutes escalation on the battlefield. If national leaders simply viewed tactical nuclear weapons as just another weapon, the escalation effects of their use would likely have been judged much less severely. Thus the taboo, by helping to define what constituted escalation in the first place, contributed to heightening decisionmakers perception of such risks during the war.
What if the United States had actually used nuclear weapons in Vietnam? From at least the time of the U.S. air strikes in response to the events of the Tonkin Gulf in early August 1964, the North Vietnamese leadership expected to be attacked with nuclear weapons. At that time, they sent women and children to the countryside, and began to plan for casualties in the millions. At no time did they ever contemplate surrender without unification with the South under Hanois leadership and ultimate control. This being so, it is difficult to see how use of tactical nuclear weapons could have made the slightest difference to the eventual outcome. The North Vietnamese fully expected to be incinerated in large numbers, and, if a nuclear attack occurred, they were prepared to persevere anyway.
The Vietnam case illustrates how, ten years after the Korean war, despite the development in the interim of all manner of small, low-yield, more usable nuclear weapons, they were less usable than ever. Although concerns about escalation clearly played a role in inhibiting their use, such concerns were powerfully reinforced by political and normative considerations. By the time of the Vietnam War, the nuclear taboo was operating with more powerful, widespread effects; it was becoming less tentative, more taken-for-granted. Further, the taboo itself became more firmly entrenched as a result of the Vietnam War. Any remaining doubts about whether the Korean War had been conducted correctly with respect to nuclear weapons were laid to rest by Vietnam, which confirmed that even tactical nuclear weapons were politically unusable. The war thus further eroded any lingering thoughts that nuclear weapons could be viewed as legitimate weapons of war.
Even Henry Kissinger was forced to confront the normative limitations on material power. Although he had written a book extolling the use of tactical nuclear weapons, he later drew away from that. Once in the White House he found to his regret that nuclear nations could not necessarily use this power to impose their will. The capacity to destroy proved difficult to translate into a plausible threat even against countries with no capacity for retaliation. He attributed this to the awesomeness of the destructive power of nuclear weapons. But as Kissinger knew well, sub-kiloton weapons are not all that awesome. So he was being a little disingenuous. But as the willingness of the North Vietnamese to fight the United States illustrated, material power alone does not make deterrence work. One of the major lessons of Vietnam for students and practitioners of international relations has been the normative and political limits on material power. Nowhere was this illustrated more clearly than in the nonuse of nuclear weapons during the war.
 Robert McNamara, In Retrospect: The Tragedy and Lessons of Vietnam (New York: Times, 1995), p. 174.
 James Blight, ed. Missed Opportunities? Revisiting the Decisions of the Vietnam War, 1945-68. Hanoi Conference, June 20-23, 1997. Transcript. Watson Institute for International Studies, Brown University, April 1998, pp. 9-10.
 This is discussed in detail in Yuen Foong Khong, Analogies at War: Korea, Munich, Dien Bien Phu, and the Vietnam Decisions of 1965 (Princeton University Press, 1992).
 William W. Kaufmann, The McNamara Strategy (New York: Harper & Row, 1964), pp. 15-16. Khong, Analogies at War.
 Daniel Ellsberg, Secrets: A Memoir of Vietnam and the Pentagon Papers (New York: Viking, 2002), p.63.
 See, for example, Henry Kissinger, Nuclear Weapons and Foreign Policy (Oxford University Press, 1957); Robert Osgood, Limited War: The Challenge to American Strategy (University of Chicago Press, 1957); Morton H. Halperin, Limited War in the Nuclear Age. (New York: Wiley, 1963).
 McGeorge Bundy, Danger and Survival (New York: Random House, 1988), p. 536.
 Ibid., p. 536.
 Bundy, Danger and Survival. He devoted only eight pages of his 735 page book on nuclear history to Vietnam.
 The Joint Chiefs of Staff objected to proposals to send a small number of U.S. troops to the region, and recommended either a large scale intervention, and even the use of nuclear weapons, or no intervention. Memo of meeting on Laos, April 29, 1961, FRUS, 1961-63, 24:150-54.
 Memo from the JCS to the Secretary of Defense, March 2, 1964, JCSM-174-64. FRUS, 1964-68, 1:115.
 PP, Vol. III, p. 623.
 PP, Vol. III, p. 238.
 PP, Vol. III, p. 175.
 Memo for the Record (W. Bundy), Discussion of Possible Extended Action in Relation to Vietnam, April 27, 1964, Executive Secretariat Conference Files, 1949-72, Box 343, Manila (SEATO) Taipei and Saigon, April 20-29, RG 59, NA. I thank William Burr for this document. Telegram from the Embassy in Vietnam to the Department of State, Saigon, May 4, 1964, in FRUS 1964-68 1: 286.
 Memo from Chairman of the NSC Working Group (W. Bundy) to the Secretary of State, November 24, 1964, FRUS, 1964-68, 1:941.
 Kaiser, American Tragedy, p. 366-7.
 Ibid., p. 360.
 PP, Vol. III, p. 238.
 PP, Vol. III, p. X
 Kaiser, America Tragedy, p. 378. Kaisers Chapter 12 provides an extended analysis of the decisionmaking process behind this report.
 By the beginning of 1963, U.S. on-shore deployments of nuclear weapons to Guam, Okinawa, the Philippines, and Taiwan grew to about 2400, a 66% increase from 1961 levels. The on-shore stockpile in the Pacific peaked at about 3,200 weapons in mid-1967, 2,600 of which were in Korea and Okinawa, and began to decrease after that. Robert Norris, William Arkin and William Burr, Where They were, Bulletin of the Atomic Scientists (November-December 1999), pp. 30-31.
 CINCPAC Command Histories for 1963, 1964, 1966. I am grateful to the Nautilus Institute for providing copies of these.
 PP, Vol. III, pp. 636, 639.
 Ted Gittinger, ed., The Johnson Years: A Vietnam Roundtable (Austin, Tex: Lyndon Baines Johnson Library : Lyndon B. Johnson School of Public Affairs), p. 64.
 Memo from the JCS to McNamara, January 22, 1964, cited in McNamara, In Retrospect, pp. 107-110; Memo from SecDef to Taylor, February 21, 1964; Memo from the JCS to McNamara, March 2, 1964, and Memo from SecDef to President, March 16, 1964, in FRUS 1964-68, 1:97-99, 112-118, 153-167.
 Memo of a Meeting with President Johnson, Washington, D.C., February 17, 1965. FRUS, 1964-68, 2:305.
 Ibid., FRUS, 1964-68, 2:305. In May 1962, Eisenhower had also recommended to Kennedy the use of nuclear weapons in the Laos crisis.
 Memo of Conversation Between Secretary of State Rusk and Prime Minister Khanh, Saigon, April 18, 1964. FRUS, 1964-68, 1:244.
 Telegram from the Secretary of State to the Department of State, Honolulu, June 1, 1964. FRUS, 1964-68, 1:410.
 See Chapters 5 and 6. David Kaiser argues that Eisenhower showed in the meeting that he had been kept well informed of the administrations policy and its rationale. Kaiser, American Tragedy, p. 403.
 Dean Rusk to the President, February 23, 1965, Deployment, vol. 2, tabs 61-87, NSCH, Box 40, NSF, LBJL, quoted in McNamara, In Retrospect, p. 173.
 NSC Executive Committee Meeting, Washington, DC, May 24, 1964, FRUS, 1964-68, 1:371.
 Memo of Conversation, Secretarys Dinner for Rumanian Foreign Minister Manescu, Washington, DC, October 14, 1965, FRUS, 1964-68, 3:455-6.
 Rusks tragic history on the Korea issue undoubtedly influenced these views. It was on his watch as Assistant Secretary of State for Far Eastern Affairs that the unexpected Chinese attack across the Yalu river in November 1950 occurred. Rusk was haunted by this all his life. Because of this, he had a tendency to see all problems of communism in Asia as threats of invasion from the north, and was blind to the fact that the problem in South Vietnam was an internal resistance movement, not preventing an invasion from North Vietnam.
 George Ball, How Valid are the Assumptions Underlying our Vietnam Policies? memo, October 5, 1964. Reprinted in The Atlantic Monthly, July 1972, pp. 41-42. Emphasis added.
 Ball, How Valid? p. 43.
 Memo from Vice President Humphrey to President Johnson, Washington, February 17, 1965. FRUS, 1964-68, 2:311. In reality, the Eisenhower administration did not rule out war with China in 1953. See Chapter 5.
 PP, Vol. III, p. 175.
 Quoted in memo from Walt Rostow to Secretary of State Rusk, November 23, 1964. PP, Vol. III, p. 645. See also Special National Intelligence Estimate, SNIE 50-2-64, Washington, May 25, 1964, FRUS, 1964-68, 1:380.
 Chen Jian, “China’s Involvement in the Vietnam War, 1964-69, The China Quarterly, No. 142 (June 1995), pp. 366-7; Kaiser, American Tragedy, pp. 439-40.
 Herring, Americas Longest War, pp. 5, 46.
 Both Ball and McNamara have since stated that they overestimated the risk of war with China. In his 1982 memoirs, Ball conceded that, in hindsight, he exaggerated the risk of the Chinese threat and possible entry into the war, but that at the time we knew almost nothing about what was going on in Chinese foreign policy. George W. Ball, The Past Has Another Pattern: Memoirs (New York : Norton, 1982), p. 505, fn. 10. McNamara described later the totally incorrect appraisal of the Chinese threat to our security but that it was a widely shared view among top officials. McNamara, In Retrospect, pp. 218-19.
 FRUS 1964-68, 2:94, 96.
 Memo from Acting Secretary of State Ball to President Johnson, February 13, 1965. FRUS, 1964-68, 2:255.
 Excerpts from Secretary Rusks Conversation with President Chiang Kai-shek, April 16, 1964. At http://www.seas.gwu.edu/nsarchive/coldwar/documents.
528th NSC meeting, April 22, 1964. FRUS, 1964-68, 1:258; Pentagon Papers, Vol. III, p. 65.
 Telegram from the Secretary of State to the Department of State, Honolulu, June 1, 1964, FRUS, 1964-68, 1:410.
 Rusk meeting with Ambassador Alphond, French Embassy, July 20, 1964. FRUS, 1964-68, 1:557.
 Memo of Conversation Between President Johnson and Prime Minister Pearson, Hilton Hotel, NY, May 28, 1964. FRUS, 1964-68, 1:395; Telegram from the Secretary of State to the Department of State, Honolulu, June 1, 1964, Ibid, p. 410.
 Lyndon Johnson, The Vantage Point: Perspectives of the Presidency, 1963-1969 (New York: Holt, Rinehart and Winston, 1984, 1971).
 Bundy, Danger and Survival, p. 537; Robert McNamara, The Military Role of Nuclear Weapons: Perceptions and Misperceptions, Foreign Affairs, Vol. 3 (Fall 1983), pp. 58-80.
 Theodore H. White, The Making of the President 1964 (New York: Athenaeum Publishers, 1965), p. 311
 Bundy, Danger and Survival, p. 537.
 Ibid., p. 538.
 See Morton Halperin, “Proposal for a Ban on the Use of Nuclear Weapons,” Institute for Defense Analyses, Special Studies Group, Study Memorandum no. 4 (Wash. D.C.: IDA, 1961); Thornton Read, A Proposal to Neutralize Nuclear Weapons (Princeton: Woodrow Wilson School, 1961); Robert Tucker, Proposal for No First Use of Nuclear Weapons (Princeton: Woodrow Wilson School, 1963).
 Walt W. Rostow, The Diffusion of Power (New York: MacMillan, 1972), p. 175.
 Fred Kaplan, The Wizards of Armageddon (New York: Touchstone, 1983), pp. 270-72. Physicist Herbert York, a weapons consultant for the government who accompanied McNamara on the trip to SAC, recalled that the visitors were just as impressed, awed, and even stunned as he had been when he first heard the war plan briefing a year earlier. Herbert York, Making Weapons, Talking Peace (New York: Basic Books, 1987) pp. 185, 204.
 York, Making Weapons, p. 204. Kaufmann, The McNamara Strategy, Ch. 2.
 McNamara to JCS Chairman, February 10, 1961, Appendix A, enclosed in JCS 2101/408, CCS 3001 Basic National Security Policy (10 February 1961), RG 218, NA, as cited in Marc Trachtenberg, The Berlin Crisis, in Trachtenberg, History and Strategy (Princeton, NJ: Princeton University Press, 1991), p. 220.
McNamara, The Military Role of Nuclear Weapons, and McNamara, In Retrospect.
Ellsberg, Secrets, pp. 57, 59.
 Ibid. pp. 59, 60.
 Ball, The Past Has Another Pattern, p. 384.
 Dean Rusk, As I Saw It (New York: W.W. Norton & Co., 1990), p. 457.
 Telegram from the Secretary of State to the Department of State, Honolulu, June 1, 1964, FRUS, 1964-68, 1:410.
 Rusk, As I Saw It, p. 248.
 Ibid., p. 366.
 Bundy, Danger and Survival, p. 537.
 Ball, How Valid, p. 42.
 Ibid., p. 42.
 The memo as a whole did have an important effect on William Bundys drafting of the options papers the following month, where option C more or less followed Balls arguments regarding Vietnam strategy. Kaiser, American Tragedy.
 Krock Papers, Mudd Library, Box 1, quoted in Kaiser, American Tragedy, p. 432
 Ibid., pp. New York Times, April 25, 1965, p. 1; April 27, 1965, p. 1,36.
 Memo from the Presidents Special Assistant for National Security Affairs (Bundy) to Secretary of Defense McNamara, June 30, 1965, FRUS, 1964-68, 3:91.
 McNamara, In Retrospect, p. 194.
 LBJ, taped conversations, 1995 release, as quoted in Kaiser, American Tragedy, p. 433.
 Ilya Gaiduk, The Soviet Union and the Vietnam War (Chicago: Ivan R. Dee, 1996), p. 73.
 Ibid., p. 47.
 Samuel Cohen, The Truth About the Neutron Bomb (New York: Morrow, 1983), p. 95, 84.
 Thomas Allen, War Games (New York: McGraw Hill, 1987), pp. 193-206.
New York Times, May 27, 1964, p. 1.
 Lawrence Wittner, Resisting the Bomb: A History of the World Nuclear Disarmament Movement, 1954-1970 (Stanford: Stanford University Press, 1998), p. 438.
 McNamara, In Retrospect, p. 150.
 Johnson received 61.1% of the popular vote and 90% of the electoral vote. White, The Making of the President 1964, pp. 315-16.
 Cohen, The Truth About the Neutron Bomb, p. 84.
 Ibid., p. 93.
 Ibid., pp. 93-94.
 Memo for Rostow from Robert Ginsburgh, 12 September 1967. Folder: Robert S. McNamara–SEA,NSF, Files of Walt Rostow, Box 3, LBJL, p. 2.
 McNamara, In Retrospect, p. 275, citing JCSM-286-67, Memo for the Secretary of Defense, Subject: Operations Against North Vietnam, May 20, 1967; and JSCM-288-67, Memo to the Secretary of Defense: Subject: Worldwide US Military Posture, May 20, 1967, CF, VN, NSF, LBJL.
 McNamara, In Retrospect, pp. 160-61, 275.
For more on the Jasons, see Gregg Herken, Cardinal Choices: Presidential Science Advising from the Atomic Bomb to SDI (New York: Oxford University Press, 1992), pp. 152-56.
 Freeman Dyson, Commentary on Jason Report, January 8, 2003.
 Steven Weinberg, communication with Peter Hayes, December 25, 2002.
Freeman Dyson, Disturbing the Universe (New York: Basic Books, 1979), p. 149.
 Dyson, Commentary on Jason Report.
 Weinberg, communication.
 Dyson, Disturbing the Universe, p. 149.
 F. Dyson, R. Gomer, S. Weinberg, and S.C. Wright, “Tactical Nuclear Weapons in Southeast Asia,” Study S-266, Jason Division, DAHC 15-67C-0011, Washington, DC, March 1967 (hereafter Jason Report). Declassified December 2002. I am grateful to Peter Hayes of the Nautilus Institute for providing a copy of it, and for his nineteen year effort to get it declassified.
 Ibid., p. 2.
 Ibid., p. 4.
 Ibid., p. 12.
 Ibid., p. 25.
 Ibid., pp. 4, 15..
 Ibid., p. 4.
 Ibid., p. 4.
 Ibid, p. 46.
 Ibid., p. 47.
 Ibid, p. 7.
 Ibid., p. 49.
 Ibid., p. 50.
 Ibid., p. 50.
 Ibid., p. 51.
 Author interview, Austin, TX, December 2, 1998.
 Jason Division: Division Consultants Who Are Also Professors are Attacked, Science, February 2, 1973, p. 461.
 Dyson, Disturbing the Universe, p. 149.
 Seymour Deitchman, Commentary on JASON report, February 25, 2003.
 Communication with author, March 3, 2003.
 Walt Rostow Papers, Tom Johnson Papers, LBJL.
 Memo to General Wheeler from Robert N. Ginsburgh, January 31, 1968, NSF, Walt Rostow Papers, Box 7, LBJL.
 Memo from Walt Rostow to President Johnson, February 3, 1968. NSF, Rostow, Box 7, LBJL.
 General Wheeler to General Westmoreland and Admiral Sharp (JCS 01154), February 1, 1968, NS Files, NSC Histories, March 31st Speech, Volume 2, Box 47, LBJL.
 Cable from General Sharp to General Wheeler (JCS 01154), February 2, 1968, NSF, NSC Histories, March 31st Speech, Volume 2, box 47, LBJL.
 Handwritten memo to Walt Rostow from Robert Ginsburgh, transmitting copies of Wheeler cable. Undated but sometime before February 10, 1968. Also Memo from Walt Rostow to the President, February 10, 1968. Both in NSF, Rostow, Box 7, LBJL.
 Memo to the President from Walt Rostow, February 2, 1968. NSF, Rostow, Box 7, LBJL.
 Memo for the President from General Wheeler, Feb 3, 1968, CM-2944-68, NSF, NSC History, March 31st speech, Vol. 6, Khe Sanh reports, A-S, Box 48, LBJL. John Prados and Ray W. Stubbe, Valley of Decision: The Seige of Khe Sanh (Boston: Houghton Mifflin, 1991), p. 291.
 Memo from Walt Rostow to President Johnson, February 3, 1968. NSF, Rostow, Box 7, LBJL.
 David M., Barrett, ed., Lyndon B. Johnsons Vietnam Papers (College Station: Texas A & M University Press, 1997), p. 722.
 William C. Westmoreland, A Soldier Reports (Garden City, NY: Doubleday, 1976), p. 338.
 Washington Post, February 12, 1968.
 Wheeler Doubts Khe Sanh will Need Atom Weapons, New York Times, February 15, 1968.
 Fulbright and Rusk Clash on Atom Talk, Washington Post, February 17, 1968.
Rumors on Use of Atomic Arms Stirred by Experts Asian Trips, New York Times, February 11, 1968. The scientists were Richard Garwin of Columbia University, Henry Kendall of MIT and Stanford, Julius P. Molnar of Bell Telephone Laboratories, and David Israel of the Defense Department.
 A-Arm Use Called Lunacy by Wilson, Washington Post, February 12, 1968.
 Letter to the President from Congressman Charles Bennett, January 31, 1968, and Letter to Charles Bennett from Barefoot Sanders, Feb 1, 1968. NSF, Country File, Vietnam, Box 102, Folder: Vietnam 7F (2)b, 12/67-3/68, Congressional Attitudes and Statements [1 of 2], LBJL.
 Public Papers of the Presidents: Lyndon B. Johnson, 1968-69, Book I (Washington, D.C.: GPO, 1970), p. 234.
 Washington Post, February 10, 1968. Two days earlier, Johnson had announced that the United States would sign the relevant protocol to the treaty creating a nuclear weapons free zone in Latin America. It committed the United States not to use or threaten to use nuclear weapons against any Latin American state party to the treaty. Public Papers, Statement by the President on the Treaty for the Prohibition of Nuclear Weapons in Latin America, February 14, 1968, p. 223.
Ellsberg, Secrets, p. 201.
 Memo from Robert McNamara to President Johnson, February 19, 1968. NSF, Rostow, Box 7, LBJL; Tom Johnson Meeting Notes, Folder: Feb. 20, 1968–1:05 pm–Tuesday lunch.
 Washington Post, February 10, 1968. Emphasis added.
 Use of Nuclear Weapons is an Invitation to Disaster, Washington Post, March 9, 1968.
 Summary of Notes by M. Bundy concerning Wise Mens meeting, March 26, 1968. Meeting Notes File, Special Advisory Group, Box 2, LBJL.
 Westmoreland, A Soldier Reports, p. 340.
 Herring, Americas Longest War, p. 205.
 Memo to the President from Walt Rostow, February 2, 1968; and Memo for the Chairman, JCS, Movement of Certain Controlled Fragmentation Munitions (COFRAM), into Southeast Asia, both in NSF, NSC History, March 31 Speech, Box 47, LBJL. Prados and Stubbe, Valley of Decision, pp. 293-4.
 Thomas W. Graham, American Public Opinion on NATO, Extended Deterrence, and Use of Nuclear Weapons: Future Fission? CSIA Occasional Paper No. 4 (Center for Science and International Affairs, Kennedy School of Government, Harvard University Press of America, 1989), pp. 14-15. Grahams study, based on the results of over 90 public opinion surveys, some never published, is the most comprehensive analysis of public opinion polling on nuclear weapons during the Cold War. For a detailed comparison of public opinion in the Korean and Vietnam wars, see John Mueller, War, Presidents and Public Opinion (New York: John Wiley & Sons, 1973).
 Graham, American Public Opinion, p. 14.
 Mueller, War, Presidents and Public Opinion, p. 105.
 Graham, American Public Opinion, p. 15.
 Blight, Missed Opportunities?, p. 88.
 H. R. Haldeman with Joseph DiMona, The Ends of Power (New York: Times Books, 1978), pp. 82-83. On Nixons madman theory, see Jeffrey Kimball, Nixons Vietnam War (Lawrence: University of Kansas Press, 1998), Ch. 4.
 In March 1955, the New York Times had reported that Nixon had warned the Chinese Communists in the bluntest terms that they would be met with atomic weapons if they embarked on any new aggression…[and] a war breaks out in the Pacific….Tactical atomic explosives are now conventional and will be used against the targets of any aggressive force….New York Times, March 13, 1955.
 Ball, The Past Has Another Pattern, p. 410.
 Roger Morris, Uncertain Greatness: Henry Kissinger and American Foreign Policy (New York: Harper & Row, 1977), p. 154.
 What the President Saw: A Nation Coming into Its Own, Time, 29 July 1985, 48-53. “Nixon Says He considered Using Atomic Weapons on 4 Occasions,” New York Times July 22, 1985. The other three occasions were during the 1973 Yom Kippur War, the intensification of the Soviet-Chinese border dispute (he made an implied nuclear threat), and the 1971 India-Pakistan war.
 “An Interview with Henry A. Kissinger: We Were Never Close to Nuclear War,Washington Post, August 11, 1985.
Stephen Ambrose, Nixon: The Triumph of a Politician, 1962-1962, (New York: Simon and Schuster, 1989), p. 223.
 Richard M. Nixon, No More Vietnams (New York: Arbor House, 1985), p. 102; Richard M. Nixon, RN: The Memoirs of Richard Nixon (New York: Grosset and Dunlap, 1978) pp. 347-8.
 Richard M. Nixon, Needed in Vietnam: The Will to Win,Readers Digest, August 1964, pp. 37-43.
 William Bundy, A Tangled Web: The Making of Foreign Policy in the Nixon Presidency (New York: Hill and Wang, 1998), p. 15.
 Ambrose, Nixon, p. 193.
Kissinger, Nuclear Weapons and Foreign Policy.
 U.S. News and World Report, March 1976.
 Terry Terriff, The Nixon Administration and the Making of U.S. Nuclear Strategy (Ithaca: Cornell University Press, 1995), pp. 54-60.
 Kimball, Nixons Vietnam War, p. 117; Terriff, The Nixon Administration , pp. 52-53; 60-69.
 SM-71-69, Haig Special File, Vietnam Files (Jan.-March 1969), Box 1007, NSC Files, NPMP.
 Memo for Kissinger from Haig, March 2, 1969, and Memo for Kissinger from Laird, February 21, 1969, Haig Special File, Vietnam Files (Jan.-March 1969), Box 1007, NSC Files, NPMP.
 Memo for Laird from Kissinger, March 3, 1969, Haig Special File, Vietnam Files (Jan.-March 1969), Box 1007, NSC Files, NPMP.
 For a discussion of what historian Jeffrey Kimball calls Kissingers disingenuous chronology of this plans evolution in his memoirs, and a careful effort to reconstruct an accurate chronology, see Kimball, Nixons Vietnam War, pp. 159-165. Kissinger implies that planning only started in September and October (rather than as early as April). His support for the plan appeared to be greater than he revealed in his memoirs.
 Seymour Hersh, The Price of Power: Kissinger in the Nixon White House (New York: Summit Books, 1983), p. 120. Kimball, Nixons Vietnam War, p. 164.
 Ibid., pp. 128-9. H. R. Haldeman, The Haldeman Diaries: Inside the Nixon White House (G. Putnams Sons, 1994), pp. 69-70, 83.
 William Burr and Jeffrey Kimball, Nixons Secret Nuclear Alert: Vietnam War Diplomacy and the Joint Chiefs of Staff Readiness Test, October 1969, Cold War History, 3/2 (January 2003).
 The September Group, as some called it, included Anthony Lake, Winston Lord, Laurence Lynn, Roger Morris, Peter Rodman, Helmut Sonnenfeldt, William Watts, Col. Alexander Haig, Col. William Lemnitzer, and Captain Rembrandt C. Robinson. Kimball, Nixons Vietnam War, pp. 163.
 Henry Kissinger, White House Years (Boston: Little, Brown, 1979), p. 284.
 Kimball, Nixons Vietnam War, p. 163.
 Vietnam Contingency Planning: Concept of Operations, September 16, 1969. I thank Jeffrey Kimball for sharing this document.
 Tad Szulc, The Illusion of Peace: Foreign Policy in the Nixon Years (New York: Viking Press, 1978), p. 150. According to Szulcs interviews, Kissinger went on to say: It shall be the assignment of this group to examine the option of a savage, decisive blow against North Vietnam, militarily. You are to start without any preconceptions at all. You are to sit down and map out what would be a savage, decisive blow. You are to examine the option from every angle, you are to examine every detail of how it should be executed militarily, what the political scenario would be. Ibid., p. 150.
 Ibid., p. 151.
 Ibid., p. 153.
 Ibid, p. 152.
 Hersh, Price of Power, p. 98. Winston Lord told Jeffrey Kimball in a 1994 interview that he was incredulous at the idea that nuclear weapons were considered. Kimball, Nixons Vietnam War, p. 163.
 Hersh, Price of Power, p. 129.
 For a full account, see Burr and Kimball, Nixons Secret Nuclear Alert.
 Nixon, Memoirs, pp. 403-5. Nixon and Kissinger later both came to regret that they backed down, holding that they should have begun aggressive bombing operations of North Vietnam much earlier, in February 1969. Kimball, Nixons Vietnam War, p. 173.
 Morris, Uncertain Greatness, pp. 165-6. Morris was an NSC staffer who resigned in 1970 over the secret bombing of Cambodia.
 Hersh, Price of Power, p. 128; Morris, Uncertain Greatness, p. 165; Kimball, Nixons Vietnam War, p. 164.
 Kimball, Nixons Vietnam War, p. 145.
 Ambrose, Nixon, p. 301; Bundy, A Tangled Web, p. 80.
 Hersh, Price of Power, p. 129.
 Ellsberg, Secrets, p. 233.
 Hersh, The Price of Power, p. 129.
 Herkken, Counsels of War, p. 17.
 White House Tapes, April 25, 1972, EOB Tape 332-25, NPMP.
 Haldeman Diary. Quotes from White House Tapes, May 2, 1972, Oval Office conversation, 717-20, NPMP.
 White House Tapes, May 4, 1972, EOB Tape 334-44, NPMP.
 White House tapes, May 5, 1972.
 Memo for the President’s files (Top Secret-Eyes Only), “National Security Council Meeting,” May 8, 1972, NPMP, NSC Files, Box 998, Haig Memcons (Jan.-Dec. 1972), p.10.
 Alexander M. Haig, Jr. Inner Circles: How America Changed the World: A Memoir. New York: Warner Books, 1992), p. 28.
 Ibid., p. 554.
 Henry Kissinger, Diplomacy (New York: Simon & Schuster, 1994), pp. 607-8.
 Peter Hayes, Pacific Powderkeg: American Nuclear Dilemmas in Korea (Lexington, MA: Lexington Books, 1991), p. 42.
 Robert S. McNamara, James G. Blight and Robert K. Brigham, Argument Without End (New York: Public Affairs, 1999), p. 407.
 Henry Kissinger, White House Years (Boston: Little, Brown, 1979) pp. 66-67.