Extended Nuclear Deterrence – Japan


The United States has extended assurances of extended nuclear deterrence to its major allies from the earliest days of the Cold War. At present, the US appears to count some 29 countries – mostly the NATO allies – under its nuclear umbrella.   Japan (like Germany, Korea and Australia) has incorporated explicit statements of reliance on United States extended nuclear deterrence into their formal defence policies. In the Japanese case these public statements reach back at least until the 1970s. The United States has frequently provided public confirmation of its promise of extended nuclear deterrence to Japan – sometimes in the form of warnings to North Korea, but also in the form of joint communiques with Japanese officials. The role of US extended nuclear deterrence in inhibiting Japanese development of nuclear weapons has become increasingly overt in recent years.

Government sources



National Defense Program Outline, National Defense Council, October 29, 1976

Japan’s basic defense policy is to possess an adequate defense capability of its own while establishing a posture for the most effective operation of that capability to prevent aggression. In addition, a defense posture capable of dealing with any aggression should be constructed, through maintaining the credibility of the Japan-U.S. security arrangement and insuring the smooth functioning of that system. Against nuclear threat Japan will rely on the nuclear deterrent capability of the United States.” (3-(1))


National Defense Program Outline in and after FY 1996, Ministry of Foreign Affairs, December, 1995

Prevent aggressions against Japan, together with the Japan-U.S. security arrangements, by possessing a defense capability of an appropriate scale which includes the functions required for defense,consistent with Japan’s geographical characteristics, taking account of the military capabilities of neighboring countries, by ensuring a posture to fully utilize the capability and by clearly showing the nation’s will to defend their own country.
Against the threat of nuclear weapons, rely on the U.S. nuclear deterrent, while working actively on international efforts for realistic and steady nuclear disarmament aiming at a world free from the nuclear weapons.” (III-4-(1)-a)


National Defense Program Guideline, FY 2005-, Approved by the Security Council and the Cabinet on December 10, 2004.

To protect its territory and people against the threat of nuclear weapons, Japan will continue to rely on the U.S. nuclear deterrent. (III-1)


Joint Statement of the Security Consultative Committee – Alliance Transformation: Advancing United States-Japan Security and Defense Cooperation, by Secretary of State Condoleezza Rice, Secretary of Defense Robert M. Gates, Minister for Foreign Affairs Taro Aso, and Minister of Defense Fumio Kyuma, May 1, 2007.

Additionally, the SCC members stressed the importance of the traditional role of the Treaty of Mutual Cooperation and Security, which has enabled a life-of-the-alliance presence for U.S. forces in Japan while providing U.S. security assurances to the Government of Japan. U.S. extended deterrence underpins the defense of Japan and regional security. The U.S. reaffirmed that the full range of U.S. military capabilities – both nuclear and non-nuclear strike forces and defensive capabilities-form the core of extended deterrence and support U.S. commitments to the defense of Japan.

Alliance BMD capabilities, which contribute to the Alliance’s overall deterrence posture, are strengthened to the extent that U.S. and Japanese systems can operate together effectively. The SCC members confirmed that, as both countries develop and deploy capabilities, every effort must be made to ensure tactical, operational, and strategic coordination. In that light, the United States and Japan will take appropriate measures, in close coordination, in response to ballistic missile threats against alliance interests.

United States

Rice Discusses North Korean Threat on Asian Trip, Peter Fedynsky, Voice of America, 20 October 2006.

Secretary Rice said no one in North Korea or Japan should doubt the United States will honor its mutual defense treaty with Tokyo. “I reaffirm the President’s statement of October 9 that the United States has the will and the capability to meet the full range, and I underscore – full range, of its deterrent and security commitments to Japan.”

Foreign Perspectives on U.S Nuclear Policy and Posture: Insights, Issues and Implications, Lewis Dunn, Gregory Giles, Jeffrey Larsen, and Thomas Skypek, Advanced Systems and Concepts Office, Defense Threat Reduction Agency, 12 December 2006.


News Navigator: Japan and the U.S. nuclear umbrella, Mainichi Shinbun, 27 August 2009

The Mainichi answers common questions some readers may have regarding the U.S. nuclear umbrella.

Q: What kind of role does the U.S. nuclear umbrella play for Japan?

A: Japan is surrounded by such nuclear powers as China and Russia, while North Korea has also carried out ballistic missile and nuclear tests. However, it’s not really clear what the U.S. would do if Japan came under nuclear attack, and it may not necessarily counterattack with nuclear weapons. There is a strong opinion in the U.S. that the country provides its nuclear umbrella to Japan to dissuade it from seeking its own nuclear capability.

Q: What if Japan got out of the nuclear umbrella?

A: If Japan scrapped the bilateral security treaty with the U.S., it could immediately get out of nuclear umbrella, but this is less than plausible. Rather than thinking about a way out of the nuclear umbrella, it is more important to build a relationship with China and North Korea to discuss, along with the U.S., what we can do to prevent nuclear weapons from being put into use. (Answers by Takashi Sudo, Political News Department)

Japan Ready for “No Nukes”, Shingo Fukuyama and Hiromichi Umebayashi, Japan Times, August 25, 2009

The goal that Obama articulated of “a world without nuclear weapons” was overwhelmingly supported by the Japanese public. Yet, the way the Japanese government views U.S. extended nuclear deterrence, otherwise referred to as the “nuclear umbrella,” is turning out to be a key sticking point, which may end up blocking progress on nuclear disarmament. Reportedly, the specific reduction in the role of nuclear weapons that is being contemplated is that they would be retained for only one purpose. Their sole purpose would be to deter the use of other people’s nuclear weapons. This is sometimes referred to as a policy of “No First Use” (NFU). The Japanese government has long taken a different undeclared view that the U.S. nuclear umbrella should also cover potential threats from biological weapons, chemical weapons and even conventional weapons. It is distressing to note that Japan is being used as an excuse to prevent Washington from making an important policy change that would be a step forward toward a world without nuclear weapons. Some argue that a reduction in the role of nuclear weapons would weaken the U.S.-Japan security relationship.

Japan, U.S. Agree On Periodic Talks Over U.S. Nuclear Umbrella, NikkeiNet, 18 July 2009

Japan and the United States agreed Saturday to set up an official framework to engage in periodic talks on the so-called U.S. nuclear umbrella over Japan and other deterrence measures, a senior Japanese official said. The move reflects the U.S. intention to remove Japan’s growing security concerns in the wake of North Korea’s nuclear test in May by deepening discussions between the two countries on the effectiveness and reliability of the nuclear umbrella, under which Japan, which does not possess nuclear weapons, is afforded protection. Through such a move, the United States may also be hoping to defuse arguments among some ruling party members in Japan that the country should arm itself with nuclear weapons. The agreement was reached at a Security Subcommittee Meeting attended by senior working-level officials from the Japanese foreign and defense ministries and their U.S. counterparts, including visiting Kurt Campbell, assistant secretary of state for East Asia and Pacific affairs.

Japan, TLAM/N, and Extended Deterrence, Hans M. Kristensen, FAS Strategic Security Blog, 2 July 2009

Admiral Timothy J. Keating, who is Commander of U.S. Pacific Command, said Tuesday that he is “unaware of specific Japanese interests in the” nuclear-armed Tomahawk Land-Attack Missile. That’s interesting because the Congressional Strategic Posture Commission recently pointed explicitly to such a Japanese interest in the role that the missile – known as the TLAM/N – provides in extending a U.S. nuclear umbrella over Japan to deter nuclear attacks against it from China and other potential adversaries in the region. We would expect the commander of Pacific forces to be in close contact with the highest levels of the Japanese government and military.  Shouldn’t he be aware of a specific Japanese interest in specific weapons for the U.S. nuclear umbrella?  So statements to the contrary in the recent Congressional Commission report seem odd and worth investigating.

Thinking About the Unthinkable: Tokyo’s Nuclear Option, Toshi Yoshihara and James R. Holmes, Naval War College Review, Summer 2009, Vol. 62, No. 3

In closing, it is worth reemphasizing that this study eschews any assessment of the likelihood of Japan’s going nuclear. Ample work already exists on the pros and cons of nuclearization. As noted in the introduction to this essay,we concur in general that it is highly unlikely that Tokyo will pursue an independent nuclear arsenal for the foreseeable future. The U.S.-Japanese alliance is arguably in the best shape ever, while mainstream Japanese policy makers remain confident in the credibility of American extended deterrence.However,we believe that this largely valid consensus on the improbability of anuclear breakout has precluded constructive discourse on practical American policy alternatives should Tokyo undertake a radical change of course.While it may be distasteful to contemplate such a scenario,we are convinced that there is genuine analytical utility in thinking about the unthinkable. Chief among our findings through this mental exercise is that Japan will not “break out” in the literal sense of the term. Rather, it will proliferate in slow motion, if it makes a decision to go nuclear.

Japanese perceptions of Obama’s nuclear ‘twin commitments’, Ken Jimbo, Japan Times, 5 March 2009.

How does Japan view U.S. President Barack Obama’s “twin commitments” to the goals of nuclear abolition and maintaining an adequate deterrent as long as nuclear weapons remain? Japan’s anticipated response to this twin commitment will reflect the dual identity of Japan’s nuclear policy. In a seeming contradiction, it wishes for the elimination of nuclear weapons while simultaneously seeking the maintenance of a credible nuclear extended deterrent.

Japan’s Nuclear Future: Policy Debate, Prospects, and U.S. Interests, Emma Chanlett-Avery and Mary Beth Nikitin, Congressional Research Service, May 9, 2008

What Are Nuclear Weapons For? John S. Foster, Jr. and Keith B. Payne, Forum on Physics and Society of The American Physical Society, Vol. 36, No. 4, October 2007

Nuclear weapons are essential to the U.S. extended deterrent.  This “nuclear umbrella” is central to the basic U.S. defense goal of assurance.  This is not a trivial goal.  The assurance provided to allies by U.S. security commitments, particularly including the U.S. nuclear umbrella, is key to the maintenance of U.S. alliance structures globally.  It is part of the basic security considerations of countries such as Japan , South Korea and Turkey. The United States can decide if the assurance of allies is a worthy continuing goal, but only our allies can decide whether they are sufficiently assured.
Japanese leaders have been explicit about the extreme security value they attach to the U.S. nuclear umbrella, and they have suggested that Japan would be forced to reconsider its non-nuclear status in the absence of the U.S. extended nuclear deterrent.  Thus, ironically, nuclear non-proliferation is tied closely to the U.S. preservation of its extended nuclear deterrent. Precisely the reverse linkage may be more the reality:  U.S. movement toward nuclear disarmament will unleash what some have called a “cascade” of nuclear proliferation among those countries which otherwise have felt themselves secure under the U.S. extended nuclear deterrent and therefore have chosen to remain non-nuclear.

Thinking the Unthinkable: Japanese nuclear power and proliferation in East Asia, Frank Barnaby and Shaun Burnie, Oxford Research Group, August 2005

??????????????? [Japan’s ‘‘Middle Power’’ Diplomacy], Soeya Yoshihide, Chikuma Shobo, 2005.

Furukawa, Katsuhisa. “Nuclear Option, Arms Control, and Extended Deterrence: In Search of a New Framework for Japan’s Nuclear Policy”, in Benjamin L. Self and Jeffrey W. Thompson (eds.), Japan’s Nuclear Option: Security, Politics, and Policy in the 21st Century, (Washington, DC: Henry L. Stimson Center, December 2003).

Halperin, Morton H. The Nuclear Dimension of the U.S.-Japan Alliance, Nautilus Institute.

Hayes, Peter “American Nuclear Hegemony in the Pacific,” Journal of Peace Research, December 1988, volume 25, no 4.

Hayes, Peter. Pacific Powderkeg: American Nuclear Dilemmas in Korea, Lexington Books, 1990.

Hughes , Llewelyn. Why Japan Will Not Go Nuclear (Yet): International and Domestic Constraints on the Nuclearization of Japan, International Security, Spring 2007, Vol. 31, No. 4, Pages 67-96

Huntley, Wade. The abolition of extended nuclear deterrence in Northeast Asia, Global Change, Peace & Security, Volume 9, Issue 2 1997, pages 39 – 56.

Jimbo, Ken. “Rethinking Japanese Security: New Concepts in Deterrence and Defense”, in Benjamin L. Self and Jeffrey W. Thompson (eds.), Japan’s Nuclear Option: Security, Politics, and Policy in the 21st Century, (Washington, DC: Henry L. Stimson Center, December 2003).

Jimbo, Ken. Deterrence and Defense in Japanese Security Policy: Regional Orientation of Extended Deterrence, Paper prepared for the second meeting of East-West Center Washington’s project on “Nuclear Weapons and Security in 21st Century Asia” 15-18 November 2006.

Mochizuki, Mike M. “Japan Tests the Nuclear Taboo”, The Nonproliferation Review, 14:2,303 — 328 (2007).

Ogawa, Shinichi. “TMD and Northeast Asian Security”, in East Asian Regional Security Futures: Theater Missile Defense Implications, Nautilus Institute, July 2000.

Schoff, James L. The U.S.-Japan Alliance & the Future of Extended Deterrence, Institute for Foreign Policy Analysis, March 2009.

Soeya, Yoshihide. Nihon no ‘‘Midoru Pawaa’’ Gaiko  [Japan’s ‘‘Middle Power’’ Diplomacy], Chikuma Shobo, 2005.

Thompson, Jeffrey W. and Benjamin L. Self. “Nuclear Energy, Space Launch Vehicles, and Advanced Technology: Japan’s Prospects for Nuclear Breakout” in Benjamin L. Self and Jeffrey W. Thompson (eds.), Japan’s Nuclear Option: Security, Politics, and Policy in the 21st Century, (Washington, DC: Henry L. Stimson Center, December 2003).

Umemoto, Tetsuya. “Missile Defense and Extended Deterrence in the Japan-US Alliance, The Korean Journal of Defense Analysis, Vol.12, No.2, (Winter 2000).

Ogawa Shin’ichi, “Link Japanese amd Koreans in a Nuclear weapon-free zone“, New York Times,

Ogawa, Shin’ichi, Problems of U.S. Extended Nuclear Deterrence for Japan”, Program on U.S.-Japan Relations, Centre for International Affairs and the Reischauer Institute of Japanese Studies, Harvard University, USJP Occasional Paper 88-13, 1988. (Part 1 [1.2 Mb], Part 2 [928 Kb], Part 3 [840 Kb], Part 4 [1.3 Mb] – all PDFs are searchable.)

See also