by Shinichi Ogawa
May 22, 2012
This report was originally presented at the East Asia Nuclear Security workshop held on November 11, 2011 in Tokyo, Japan. All of the papers and presentations given at the workshop are available here, along with the full agenda, participant list and a workshop photo gallery.
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Shinichi Ogawa explores the probability of Japan heightening its conventional deterrence capabilities and the possible ways in which it may do so. His report first evaluates how Japan might augment its defensive capabilities (and invest in offensive weapons) were it’s military relationship and security guarantees with the United States to dissolve. He then assesses possible changes to Japan’s conventional military capabilities were the United States to maintain its ‘nuclear umbrella’ over Japan–and whether or not this arrangement could be compatible with a Northeast Asian Nuclear Weapons Free Zone.
Shinichi Ogawa is a visiting professor at Ritsumeikan Asia Pacific University.
The views expressed in this report do not necessarily reflect the official policy or position of the Nautilus Institute. Readers should note that Nautilus seeks a diversity of views and opinions on significant topics in order to identify common ground.
“Conventional Deterrence and Japan’s Security”
by Shinichi Ogawa
This paper first explores whether or not Japan’s own conventional defense can provide Japan with a reasonably reliable deterrent. The exploration deals with rather an extreme scenario, since a defense posture wherein Japan relies solely on its own conventional forces implies the breakup of the U.S.-Japan alliance, withdrawal of U.S. forces from Japan, and that Japan no longer enjoys U.S. extended nuclear and conventional deterrence.
The report subsequently discusses conventional deterrence for Japan based on the U.S.-Japan defense cooperation under the shadow of implicit U.S. extended nuclear deterrence. In view of the growing tendency that the U.S. would refrain from threatening to use its nuclear weapons with the exception of highly limited scenarios, studying various requirements for a successful conventional deterrence has become all the more important.
Japan’s Home-grown Conventional-only Defense
A Japan that no longer enjoys the U.S. defense umbrella but is still determined to be non-nuclear has to examine the viability of indigenous conventional-only defense and deterrence. In order to attain a certain degree of conventional deterrence Japan must first revise its long-standing defense doctrine and posture. Under the post-World War II Japanese Constitution, Japan has limited its defense capability to a “minimum necessary capability for self-defense” and defined its defense posture as “exclusively defensive-defense.” The minimum necessary capability for self-defense may vary with the prevailing international situation, military capabilities of would-be adversaries, and military technologies available, but offensive weapons designed to be used only for the destruction of another country, such as long-range offensive missiles, long-range bombers, and attack aircraft carriers are not allowed under any circumstances. This prohibition, coupled with a doctrine of exclusively defensive-defense, has led to additional self-restraint on the part of Japan, which refrains from deploying any power projection capability or offensive military capability that can strike other countries’ territories. The present guidelines for U.S.-Japan defense cooperation, adopted in 1997, can read that Japan’s Self-Defense Force (SDF) assumes defensive operations in and around Japan, while U.S. forces provide the strike power necessary for defending Japan.
Without this U.S. defense commitment, Japan would have to develop its own offensive capabilities to a certain extent in order to build its own deterrence. A purely denial defense posture lacking both offensive and retaliatory military capabilities is inherently a much weaker deterrent than the one that combines both defensive and offensive capabilities. If a prospective attacker were faced with simply with a defensive power, it could estimate how much effort it would have to invest and what its probable losses would be in order to defeat the enemy forces. If, however, the challenger were confronted with some offensive and retaliatory capabilities, it would be more difficult for the country to estimate the total costs it would have to pay. Precisely this uncertainty makes the threat of offense and retaliation a strong deterrent. Japan’s exclusively defensive-defense posture is a sort of political concept and indicates that Japan will not engage in an aggressive war or in a surprise attack and that Japan will only fight in self-defense. However, a majority of the Japanese public tends to extend the political concept to actual military operations and interprets it as prohibiting the SDF from launching offensive operations. There should be no undue restraint imposed on military operations as such once the political decision to employ the SDF has been made. There is no reason why a politically defensive posture cannot have a militarily offensive power and strategy. Such power and strategy is indispensable for building Japan’s own deterrent capacity.
The second requirement for achieving Japan’s conventional deterrence is to augment its newly acquired offensive capability by developing and deploying advanced sensors and high-tech precision-strike weapons, supported by computerized information processing. Thanks to revolutionary advances in military and information technology, America’s conventional weapons attained an extraordinary destructive power by the beginning of the 1990s. Today’s U.S. conventional forces seem to have a combination of range, accuracy, survivability, and lethality that allows them to strike deep into adversaries’ territories. In order to design conventional-only deterrence, Japan has to develop and deploy powerful high-tech conventional weapons with the destructive capabilities closer to those fielded by the United States.
Several difficult problems, however, defy Japanese efforts to attain credible high-tech conventional deterrence. First, high-tech conventional weapon systems, to be sufficiently compelling, might be financially costly to implement. In order to make a conventional threat that is by nature a less frightening one into an awesome threat, Japan has to allocate a large amount of funds to a range of high-tech conventional weapon systems such as theater-range precision-guided munitions (PGM), including the needed delivery platforms and supporting systems. In view of Japan’s severe fiscal condition that suffers from a huge amount of national debt reaching almost 200 percent of the value of its annual GDP, bearing the new costs for developing and fielding high-tech weapons and their means for delivery simply looks prohibitive. The fact that the annual Japanese defense budget in the last ten years has not increased a bit, despite the worsening condition of its security environment, vividly illustrates Japan’s fiscal difficulties.
Second, even if Japan should somehow succeed to some degree in developing and deploying lethal high-tech conventional weapons, it is still likely to face difficulty convincing its adversaries of the destructive power of the newly acquired weapons. This is simply because, in contrast to U.S. forces, the SDF under the strict constraints on the use of force will not have sufficient chances to demonstrate their destructive power. New, untried capabilities may have little deterrent impact.
Other problems that may emerge in the process of Japanese conventional buildup are the possible negative reactions from neighboring countries. Because of a series of wars Japan waged in the end of the 19th century and first half of the 20th century, Japan’s deployment of power projection capabilities, even for deterrent purposes, is likely to invite countermeasures from the two Koreas and probably even from nuclear-armed China and Russia, thereby creating a serious security dilemma. In order to avoid such a quandary, Japan may be forced to compromise on its development program of high-tech conventional weapons. Alternatively, Japan may advocate multilateral arms control to restrain some conventional weapons, for the purpose of mitigating the prospects of an arms race in Northeast Asia. Such an undertaking, however, would prove to be impractical due to vast differences of conventional force structure among Northeast Asian states and difficulties caused by the nuclear weapons that some regional states deploy. In view of these financial, political, and historical barriers, Japan is unlikely to be able to develop and field high-tech conventional forces necessary for home-grown conventional deterrence.
Moreover, even though high-tech conventional weapons have acquired upgraded destructive power, nuclear weapons, with their quick and vast destructive power, are still more effective than conventional weapons in making strategic strikes. Consequently, a conventional-only defense gives a nuclear-armed aggressor a decisive war-winning capability; deterrence vis-à-vis a nuclear-armed adversary is hard to be successful through exclusively conventional means. Further, questions remain in the so-called “intra-war deterrence” situation or capabilities to stop combat action from escalating. Under circumstances where a nuclear-armed adversary is already experiencing effects of Japanese high-tech conventional strikes as part of an ongoing war, it is doubtful that a threat of additional high-tech conventional strikes could powerfully deter the opponent’s use of nuclear weapons. It is doubtful that conventional weapons, albeit enhanced in their strike capabilities, can reliably dissuade a nuclear-armed state from escalating conventional war to the nuclear level; the country with conventional-only defense would be forced to back down if the nuclear-armed adversary threatens to use nuclear weapons strategically during conventional hostilities. Furthermore, due to the horrifying experiences in Hiroshima and Nagasaki, the Japanese public at large suffers from psychological weakness toward nuclear threat and coercion. Nuclear-armed adversaries can exploit this Japanese vulnerability in a crisis or during wartime.
To exclude nuclear weapons from deterrence calculus, Japan may propose an establishment of a region-wide, legally binding negative security assurance (NSA) regime. Nevertheless, even if Japan was successful in such an undertaking, such a regime is still not assuring enough for the Japanese public since there is no viable means to verify nuclear-armed states’ commitment not to use nuclear weapons. For a country like Japan that cannot rule out the danger of facing a nuclear threat, conventional-only defense cannot generate enough assurance of its security. As long as nuclear weapons continue to exist in neighboring states, Japan needs a nuclear-based deterrent to cope with them.
Characteristics of U.S. Extended Nuclear Deterrence to Japan
In the Cold War days, in contrast to Western Europe, the U.S. and Japan did not find it absolute necessary to deploy U.S. nuclear weapons on Japanese territory in maintaining the credibility of the U.S. nuclear umbrella. The reason was as follows. Japan never faced a Soviet conventional threat of the same type and magnitude as that confronted by Western Europe. The Soviet conventional threat posed to Japan was alleviated considerably by Japan’s island position and the existence of China, which then had pinned down considerable Soviet forces. Thus, the conventional military balance, specifically that of air and naval forces confronting the Soviet Union, were not adverse when considering the forces of the U.S. and Japan combined; consequently, the U.S. did not need to rely heavily on nuclear weapons to defend Japan. The nuclear shield Japan enjoyed was, in essence, a U.S. retaliatory nuclear deterrent against a Soviet nuclear first use on Japan, which did not necessarily require deployment of U.S. nuclear weapons on Japanese territory. Japan’s three non-nuclear principles, announced in December 1967 for domestic political reasons and contains a provision of non-introduction of nuclear weapons into Japan, did not seriously damage the credibility of the U.S. nuclear commitment.
Judging from our experience in the Cold War, as long as the combined Japanese and U.S. conventional forces can maintain an adequate air and naval balance vis-à-vis a neighboring nuclear-armed state, the requisite function of the U.S. extended nuclear deterrence for Japan would continue to be the prevention of the first use of nuclear weapons by a nuclear adversary. Such a purely retaliatory deterrent posture does not require a particular type of nuclear weapon or specific deployment and employment policy. The existential nature of U.S. nuclear deterrence would be sufficient. In addition, such deterrence can be buttressed by periodic U.S. declarations of its nuclear commitment to Japan. Moreover, overwhelming counterforce capabilities of U.S. strategic nuclear forces, compared with those of other nuclear-armed states, make the existential U.S. extended nuclear deterrence even more workable.
The aforementioned discussion suggests that if Japan and the U.S. continue to maintain an adequate air and naval balance in comparison with opponents, the non-introduction clause of Japan’s three non-nuclear principles does not hamper the U.S. policy of extending nuclear deterrence. If that is the case, we can further argue that a carefully designed nuclear-weapon-free zone (NWFZ) covering Japan and South Korea  is not incompatible with U.S. extended nuclear deterrence to Japan and South Korea, providing once again that each of the two countries, with U.S. assistance, maintains conventional military capabilities necessary for coping with a conventional assault from a neighboring nuclear adversary.
A question remains, however. What will become of U.S. troops stationed in Japan and South Korea when the two countries attempt to establish a NWFZ? From Japan and South Korea’s point of view, U.S. conventional forces deployed in each country are the ultimate symbol of U.S. resolve and commitment to their security. Indeed, stationing of combat-ready U.S. conventional forces on their soil exerts a powerful deterrent effect on a nuclear-armed opponent by negating the scenario that a nuclear-armed adversary could launch a conventional attack against Japan or South Korea and, after achieving a quick victory, could issue a nuclear threat in with the expectation that the U.S. would choose not to intervene. Accordingly, Japan and South Korea will find it difficult to trade Japan- and Korea-based U.S. forces for creating a NWFZ.
A neighboring nuclear opponent, on the other hand, may view that engaging fully with forward-deployed U.S. forces in the Asia Pacific region including those stationed in Japan and South Korea can threaten its homeland security and/or inescapably link, however remote, to nuclear dimensions. Thus, the neighboring nuclear weapon state argues that stationing of a sizable U.S. force in a state party to a NWFZ contravenes the spirit of NWFZ, if not its provisions. In addition, if the U.S. deploys in Japan or South Korea longer-range PGMs with a considerable counterforce capability against the nuclear forces of the nuclear opponent, such a line of argument unavoidably grows. If so, it is not surprising that the nuclear-armed opponent tries to mutilate or deny a legally binding NSA to Japan and South Korea, thereby negating one rationale for establishing a NWFZ.
One may invoke Australia’s unique position to disprove the afore-mentioned argument. Both China and Russia have given a legally binding NSA to Australia,  a party to the South Pacific Nuclear Free Zone Treaty and a staunch ally of the United States. While Australia has not placed combat-ready U.S. troops on its territory (except for periodic joint training), it has been hosting joint military facilities related to U.S. nuclear employment policy such as the one at Pine Gap for ballistic missile early warning information and other intelligence collection. However, Australia is located in the Southern Hemisphere and is largely immune from strategic competitions staged in Northeast Asia where the national interests of China, the United States, South Korea, Russia, and Japan converge.
Conventional Deterrence under the Existential U.S. Nuclear Umbrella
America’s 2010 Nuclear Posture Review (NPR) Report has announced a strengthened NSA vis-à-vis non-nuclear weapon states that are compliant with the NPT, but declared as in the past to maintain an option for a nuclear response to a non-nuclear assault by a nuclear-armed state or non-nuclear weapon state not compliant with the NPT. At the same time, however, the NPR stresses that the U.S. would consider the use of nuclear weapons only “in extreme circumstances,” and only when the “vital interests” of the U.S. and its allies are at stake. Furthermore, it confirms that the U.S. is determined to further strengthen its conventional weapons capabilities with the objective of making deterrence of a nuclear attack on the U.S. or its allies the “sole purpose” of its nuclear arsenal. In short, the chance of U.S. nuclear response, except in the case of a nuclear attack on it or its allies, is likely to be highly limited on condition that adversaries’ non-nuclear attack remains incapable of making a strategic strike.
Decreasing the weight of nuclear component in U.S. extended deterrence should not be interpreted as damaging its credibility. Rather, relying a lot on nuclear weapons may lead adversaries to doubt U.S. resolve. The historical fact that several non-nuclear weapon states initiated war against nuclear-armed states illustrates the limitation of nuclear deterrent against conventional attack. The history of non-use of nuclear weapons suggests that the gravity of moral and political consequences accompanying the use of nuclear weapons outweighs the military advantage of using them. Nuclear weapons have shown inherent limitations in preventing war between nuclear powers and non-nuclear weapon countries. Moreover, the longer the history of non-use of nuclear weapons, the more incredible would be the threat to use nuclear weapons against non-nuclear weapon states, thus downgrading deterrent value of nuclear weapons.
The trend that the U.S. extended deterrence will rely more on conventional means does not necessarily make it less credible. Conventional weapons can exert their own deterrent effect. In contrast to nuclear weapons, high-tech conventional weapons permit selective attacks and minimize secondary damages and, therefore, are more usable, thereby making their deterrent threat more credible.
While conventional weapons have their own deterrent power, success of extended conventional deterrence in itself cannot be an easy task to achieve: whereas threats for central deterrence are inherently credible, threats for extended deterrence have to be made credible. One past study on extended deterrence argues that out of fifty-eight cases of attempted extended deterrence from 1885 to 1984, the failed deterrence counts as many as twenty-four cases. The other past study contends that deterrence is most often defeated by the flawed calculations of the challengers. Then what type of weapons, deployment posture, employment strategies, and relations between protector and protégé can dissuade the challenger from launching military actions, or conversely can be most conducive to the success of extended conventional deterrence?
First, Japan, in addition to maintaining an overall air and naval balance, with U.S. assistance, vis-à-vis each of the neighboring nuclear adversaries, must reconfirm that one indispensable element for a successful extended deterrence is the deployment of U.S. combat-ready troops on Japanese soil. As mentioned before, stationing protector’s force on the soil of a protégé is the ultimate, visible symbol of defender’s will to commit to the protégé’s defense. Further, Japan has to maintain and help manage U.S. military bases and facilities in Japan to ensure their smooth functions. Without access to en route and in-theater logistical and basing support, the U.S. cannot conduct pre-planned military operations and bring in necessary reinforcing force in wartime.
Another important U.S. backup is the continued deployment of strike power in the Asia Pacific region, which Japan has kept away from for political reasons. These include carrier-based air wing, land-based fighter aircraft that can carry out land-attack mission, Guam-based bombers with precision-strike capabilities, and newly deployed nuclear-powered guided missile submarines (SSGNs)—former ballistic missile submarines converted to carry conventional cruise missiles. Unlimited expansion of deep-strike high-tech conventional weapons is provocative and thus not desirable; but some of these weapon systems can execute effective counter-offensive and counterforce operations, thereby buttressing deterrence by denial.
Third, Japan has to deploy a requisite level of conventional force in and around the remote island areas of potential conflict for preventing its opponent from achieving a quick fait accompli and for fighting until the U.S. brings in a reinforcing force. This appeal applies to the area of the Senkaku Islands that China has long claimed. The Senkaku issue poses Japan a daunting task for deterrence success. For one thing, the disputed area is very close to mainland China. China’s advantage in geographical closeness may lead the Chinese leadership to believe that it can capture the Islands by force, through rapid operations. States contemplating conventional aggression typically seek a quick, low-cost victory. Accordingly, it is the local and immediate military balance in the conflict area that would most influence China’s calculations regarding a quick victory. Thus, it is crucial for Japan to ensure that China does not believe itself to have a local military advantage. To avoid further China’s miscalculation and to buttress deterrence still more, Japan, arguably with U.S. support, needs to prepare for protracted conventional hostilities, by improving its sustainability of war fighting through securing fuel and ammunition supplies. Higher probability of a drawn-out fighting effectively dissuades adversary from challenging the status quo ante.
Yet the Senkaku issue poses Japan a still more intractable problem in the context of deterrence: China is dissatisfied with the status quo and has been laying claim to the Senkaku as its own territory. In view of prevailing nationalism and/or anti-Japanese nationalism observed in the Chinese society, the Chinese leadership may, especially if they face some domestic problems in the future that seriously challenge their legitimacy, feel compelled to capture the Senkaku in order both to accommodate anti-Japanese nationalism and to salvage their failing regime. In such a situation, the Chinese leadership may take substantial risks of fighting a prolonged war against Japan and the United States, for fear of intolerable loss its lukewarm action might bring about. In order to deal with such Chinese military actions, Japan and the U.S. have to prepare for sufficient capabilities for defeating China in the early stages of hostilities so that China cannot hope to seize the Islands in a drawn-out war.
Fourth, in order to bolster conventional deterrence, Japan must pursue development and deployment of enhanced ballistic missile defense (BMD) system, even granting that it is not an easy task for Japan to develop and deploy BMD systems that can surpass offensive ballistic missile force in terms of cost-effectiveness ratio. Aside from nuclear-armed ballistic missiles, the military significance of ballistic missile is largely dependent upon its accuracy. If circular error probable (CEP) of ballistic missile is, say, around one kilometer, its military effects are insignificant, excepting its effects as a means for political terrorization. However, as the accuracy of ballistic missile substantially improves, ballistic missiles can become capable of fulfilling conventional missions. It is not easy to estimate when Japan’s neighboring states can attain the degree of accuracy sufficient for carrying out such mission, but it is a matter of time that they achieve substantially higher ballistic missile accuracy. If Japan’s neighboring states deploy conventionally-armed ballistic missiles capable of striking accurately Japan’s political center or nuclear power plants scattering along the coast of the Sea of Japan, Japan could be inversely deterred. In addition, if U.S. forces stationed in Japan are vastly vulnerable to the threat of ballistic missile attack, they cannot conduct flexible military operations. To maintain smooth and efficient operation of the U.S.-Japan military cooperation, it must be avoided that U.S. forces on Japanese soil are taken as a hostage of ballistic missile threat.
The potential threat of land-attack cruise missile (LACM) is more imminent than that posed by ballistic missiles. Cruise missiles are cheaper as well as easier to be made more accurate and longer-ranged than ballistic missiles. They are more suitable for carrying chemical weapons than ballistic missiles. Major possessors of cruise missiles in Northeast Asia are Russia, China, and North Korea, of which Russia and China have been deploying land-attack varieties. North Korea’s cruise missiles are anti-ship missiles, but no one can deny the possibility that Pyongyang may develop and deploy land-attack versions.
The PAC-3 system is supposed to have a certain capability for intercepting cruise missiles. Cruise missiles, however, cannot always be captured by sensor/radar since they are, unlike ballistic missiles, flying at a low altitude. In addition, fire signals can hardly be detected and launch sites are not fixed. For that reason, in addition to the PAC-3 system another defense measure against cruise missiles must be taken. To cope with cruise missiles, it is effective to intercept a cruise missile in depth along its flying route. Instead of separately operating interceptors from fighter plane, surface vessels, or ground base, it will be vital to create a battle management system for tied-up operation of air-, sea-, and land-based intercepting missiles by providing a unified command, control, and combat capability to aircraft such as those equipped with airborne warning and control system (AWACS).
Whereas credibility of extended nuclear deterrence is largely dependent on the resolve of protector, the credibility of conventional deterrence is based on military capabilities, the threat to deny an adversary the ability to achieve its military objectives through defensive and offensive operations. Ideal force structure for a successful conventional deterrence, however, requires some degree of punishment capability against non-military high-value targets, since some adversary may be ready to accept greater casualties and willing to fight longer and harder.
There are some other important yardsticks Japan should note in preparing for conventional defense and deterrence. It is crucial for the SDF to maintain higher readiness and enhance interoperability between the SDF and U.S. forces. In addition, the SDF should promote joint military exercise with U.S. forces, thereby ensuring smooth combined operations during hostilities. U.S.-Japan joint military drills are particularly important, since the SDF and U.S. forces are not fully integrated and operate through a respective chain of command.
Furthermore, it is desirable that the Japanese government return to the previous position that it would cope on its own with limited and small-scale aggression, such as attacks on offshore islands. That posture could have an effect of conveying Japanese resolve to safeguard its territorial integrity not only against a potential adversary but also to the United States, thereby strengthen the U.S. will to commit to Japan’s defense. However, the 1995 National Defense Program Guidelines (NDPG) and the NDPG onward and the 1997 Guidelines for U.S.-Japan Defense Cooperation anticipate U.S. military involvement and assistance from an early phase of such limited and small-scale conflicts. Too much dependence breeds contempt and distrust.
Although extended conventional deterrence is largely based on military capabilities, non-military dimensions of extended deterrence are no less important than military capabilities. Closer economic and political ties between the U.S. and Japan reinforce the credibility of American guarantee to Japan. While strong bonds of mutual identification and sympathy, or “we feeling,” between the two nations add still more to the credibility, cultural and historical differences between the two countries lie in the path of achieving such strong bonds. Thus the government and people of Japan, along with efforts to advance mutual sympathy, have to strive for closer and mutually beneficial economic and political cooperation.
Finally, the U.S. and Japan must make further efforts to stabilize the security environment of the Asia Pacific region, thus alleviating the security challenges that deterrence and defense mechanisms have to be invoked. In particular, it is quite important for the two countries to build mutual trust and develop cooperative relationships with China and Russia, both of which have a significant influence on the security of Japan and the region at large.
 The 1997 Guidelines for U.S.-Japan Defense Cooperation declares, “The Self-Defense Forces will primarily conduct defensive operations in Japanese territory and its surrounding waters and airspace, while U.S. Forces support Self-Defense Forces’ operations. U.S. Forces will also conduct operations to supplement the capabilities of the Self-Defense Forces.”
 Then-vice president Dick Cheney, after the Operation Desert Storm, reportedly went as far as to say that U.S. high-tech conventional weapons had grown to be able to fulfill the missions previously achievable only with nuclear weapons. Quoted in William M. Arkin et al., “Nuclear Weapons Headed for the Trash,” The Bulletin of the Atomic Scientists, vol. 47, no. 10 (December 1991), p. 16. For another example, William J. Perry, before assuming office as the secretary of defense under President Bill Clinton, estimated that U.S. high-tech conventional weapons could enable the U.S. to limit the role of its nuclear forces to the deterrence of nuclear attack alone. See, William J. Perry, “Desert Storm and Deterrence,” Foreign Affairs, vol. 70, no. (Fall 1991), p. 66.
 In contrast, Russia’s annual defense budget has grown to be about six times larger and China’s defense budget has amounted about 3.7 times larger than that of ten years ago. See Boueishou [Ministry of Defense, Japan], Nippon no Bouei Heisei 23 [White Paper on Defense 2011] (Gyosei, 2011), pp. 204, 207. http://www.clearing.mod.go.jp/hakusho_data/2011/w2011_00.html
 The Japanese Constitution prohibits the government to employ the SDF to solve international disputes. The Japanese government restricts the use of force only for self-defense and under the following three conditions: 1) when there is an imminent and illegitimate act of aggression against Japan; 2) when there is no appropriate means to deal with such aggression other than by resorting to the right of self-defense; and 3) the use of armed force is confined to the minimum necessary level.
 For the details, see Shinichi Ogawa, “U.S. Nuclear Forces and Japanese/Western Pacific Security,” in Nuclear Weapons in the Changing World: Perspectives from Europe, Asia, and North America, ed. Patrick J. Garrity and Steven Maaranen, (New York: Plenum Press, 1992), pp. 150-151.
 Japan, Ministry of Foreign Affairs, Disarmament, Non-proliferation and Science Department, Nippon no Gunshuku・Fukakusan Gaiko [Japan’s Disarmament and Non-Proliferation Policy] 5th edition, (n.a., 2011), p. 186.
 Australia, Department of Defence, Defence White Paper 2009, pp. 94-95. http://www.defence.gov.au/whitepaper/docs/defence_white_paper_2009.pdf
 Some examples are China’ military intervention in the Korean War, North Vietnam’s offensive operations against the U.S. in the Vietnam War, surprise attack by Egypt and Syria against Israel in the Yom Kippur War (the Fourth Arab-Israeli War of 1973), and the 1982 Falkland War opened by Argentina.
 Thomas C. Schelling, Arms and Influence (New Haven: Yale University Press, 1966), p. 36. Patrick Morgan articulates this as follows: “One of the perceptual problems of deterrence on behalf of third parties is that the costs a state is willing to bear are usually much less than if its own territory is at stake, and it is very difficult to pretend otherwise.” See Patrick M. Morgan, Deterrence: A Conceptual Analysis (Beverly Hills: Sage Publications, 1977), p. 84.
 Paul K. Huth, Extended Deterrence and the Prevention of War (New Haven: Yale University Press, 1988), pp. 23-26. Another study reveals that out of 12 major instances of conventional deterrence between 1938 and 1979 only two cases represented clear-cut deterrence successes. See John J. Mearsheimer, Conventional Deterrence (Ithaca: Cornell University Press, 1983), pp. 19-20.
 The United States, however, has to remain cautious not to generate a countervailing interest in nuclear weapons by the adversaries who lack the resources to compete with U.S. high-tech conventional weapons.
 Huth, Extended Deterrence and the Prevention of War, pp. 39-41, 74, 76. Michael S. Gerson, “Conventional Deterrence in the Second Nuclear Age,” Parameters, vol. 39, no. 3 (Autumn 2009), p. 38. Another conditions contributing to a success of extended conventional deterrence are: when any previous crisis involving the same adversaries resulted in stalemate rather than clear victory for either and when the military and diplomatic bargaining process is characterized by tit-for-tat or firm-but-flexible strategies rather than bullying or appeasement. Paul Huth and Bruce Russett, “Deterrence Failure and Crisis Escalation,” International Studies Quarterly, vol. 32, no. 1 (March 1988), p. 29.
 The present Japanese air defense is designed to operate separately: low-air space defense by deploying the Ground Self-Defense Force’s surface-to-air missiles, high-air space defense with PAC-1/PAC-2 operated by the Air Self-Defense Force and maritime air defense by the Maritime Self-Defense Force, mainly with Aegis ships.
 The 1976 National Defense Program Guidelines (NDPG) and the 1978 Guidelines for U.S.-Japan Defense Cooperation stipulated, “Japan will, in principle, independently fend off limited and small-scale invasions.” It is not clear why the Japanese government gave up this posture, but the 2011 White Paper on Defense simply writes that “[I]n consideration of the expanded role of the defense capabilities, this stipulation was considered inappropriate as it focused solely on invasions of Japan…”
 Given the growing Sino-U.S. economic interdependence and trade volume between the two countries that amounts to more than two times larger than that of U.S.-Japanese trade, one may wonder if it really would be in the American national interest to defend Japan should China and Japan went into a military conflict. Despite possible large economic costs to the U.S. incurred by a Sino-U.S. military confrontation, Professor Joseph S. Nye argues that the U.S. would still find it in the American interest to defend Japan since China poses a potential threat to the United States while Japan does not, and the U.S. shares democratic values with Japan while China is not a democracy. Joseph S. Nye, Jr., Prepared Statement for the House Foreign Affairs Committee, Subcommittee on Asia, the Pacific and the Global Environment, Hearing on “Japan’s Changing Role,” June 25, 2009, p. 4. http://www.hcfa.house.gov/111/50632.pdf
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