East Asia Nuclear Policy Project
Morton H. Halperin, The Nuclear Dimension of the U.S.-Japan Alliance

Section 5, "U.S. Nuclear Policy and Japanese Nuclear Weapons"


U.S. Nuclear Policy and Japanese Nuclear Weapons

The debate within the U.S. government about how to address the problem of nuclear proliferation remains unresolved thirty years after the United States agreed with the Soviet Union to sponsor a non-proliferation treaty.

Originally, supporters of the non-proliferation treaty within the U.S. government argued that the only way to prevent the proliferation of nuclear weapons was to establish an international norm that states should not develop nuclear weapons. In order to secure wide acceptance of such an agreement, the United States and the other nuclear powers needed to agree to certain conditions, including a commitment not to use or threaten to use nuclear weapons against states that had renounced the right to make nuclear weapons; in turn, such states had to be assured of cooperation in developing nuclear power and receive at least minimal security guarantees against nuclear threats. Finally, the United States had to agree to move toward reducing its reliance on nuclear weapons and its own nuclear arsenal and to accept limits-to be embodied in the non-proliferation treaty-on its ability to share information about nuclear weapons with its allies.

It was this last provision that provoked the most controversy within the U.S. government. Skeptics stressed the importance of sharing nuclear information and the operational planning and control of nuclear weapons with U.S. allies. From this perspective, the way to prevent key U.S. non-nuclear allies, Germany and Japan, from developing nuclear weapons was to maintain a robust nuclear capability and to seek a way in which to draw those two nations into participating in the decisions regarding those nuclear forces. In Europe, this led to proposals for a Multinational Force (MLF) in which a group of nations, including Germany, would provide military personnel for a ship equipped with U.S. nuclear armed missiles; others believed that the option of France sharing its nuclear force with Germany needed to be maintained. Furthermore, in what was then known as the Far East, the focus during the 1950s and 1960s was on "educating the Japanese about nuclear weapons" so that Japan would permit the stationing of nuclear weapons on its territory and participate in the planning for their use along with South Korea, which by 1958 had agreed to allow the United States to store nuclear weapons in its territory.

Not surprisingly, this conflict within the U.S. government resulted in a compromise. The United States negotiated the NPT but did not, at least in the first years of the Nixon administration, press other nations to sign. It negotiated a treaty with no negative or positive security assurances and gave only the most minimal assurances through the U.N. Security Council. Restrictions on sharing nuclear information were left loose enough to permit both the NATO Nuclear Planning Group to continue and the United States to train willing allies in the use of nuclear weapons. Finally, commitments to reduce nuclear forces in that treaty were consigned to a hortatory preamble.

Today, the school of thought that had opposed the NPT as an effective means by which to prevent nuclear proliferation still argues that U.S. enemies must be deterred with threats and allies assured by a robust U.S. nuclear arsenal backed by a clear willingness to employ nuclear weapons. They view the commitment in the NPT to move toward nuclear disarmament as mere rhetoric and, in any case, well-satisfied by the steps the United States has taken-and continues to take-to reduce its nuclear arsenal both unilaterally and by international agreement.

I believe that this approach is profoundly misguided as it applies broadly, but here I want to focus only on Northeast Asia in general and on Japan in particular.

Throughout the postwar period, Japanese leaders have quietly debated the question of whether Japan should develop an independent nuclear capability.29 This debate was not centered around the credibility of the U.S. deterrent. Given the lack of any clear threat to Japan and the importance of the United States to Japan, few Japanese leaders have argued that more needed to be done to prevent nuclear threats to Japan. Given the conventional balance in Asia, the question of whether nuclear weapons should be used in response to conventional attacks has never been in the forefront of the debate. Neither the Russians nor the Chinese could have any doubt that an attack on Japan would be viewed as an attack on the United States, and so the U.S. nuclear threat was seen as a sufficient deterrent.

In fact, while some Japanese have doubted the credibility of the U.S. nuclear deterrent,30 most Japanese who leaned toward advocating a Japanese nuclear capability took this position because they believed such a capability would permit Japan to end the security relation with the United States and to assert an independent role in the world. Yet despite the deep desire of many Japanese leaders to regain Japanese independence, there were three major obstacles to moving in this direction. First, the Japanese people would not tolerate the massive increase in defense spending, the assertion of an independent military role, or, most of all, the development of nuclear weapons. Second, the reaction in the rest of Asia would pose a very serious threat to Japan's economic goals as well as to its security. Finally, Japanese leaders recognized that it would be very difficult to develop a secure second strike capability against the Soviet Union.

Even if Japan had developed nuclear weapons, it still might have needed the U.S. nuclear deterrent to ensure that the Kremlin was not tempted to launch a surprise attack. Thus, developing nuclear weapons would still have left two problems. First, since the very purpose of developing a nuclear capability was to assert independence from the United States, it made no sense to simultaneously seek to rely on the U.S. deterrent. Second, given the U.S. anti-proliferation posture, Japan risked losing the protection of the U.S. deterrent if it set out on this path. Therefore, Japan saw no choice but to sign onto the NPT and later to accept making it permanent, while quietly maintaining its options so that it could respond if the international and domestic situation made it possible for Japan to acquire a nuclear capability.

The end of the cold war changed this situation in only one way. The collapse of the Soviet Union and the drastic decline in the Russian economy- and hence the resources available for defense-meant that it became possible for Japan to develop its own nuclear deterrent sufficient to deter both Russia and China. However, the other impediments to moving forward remain.

We come then to the fundamental question: which U.S. nuclear posture is most likely to solidify the Japanese non-nuclear posture?

U.S. policy continues to be premised on the assumption that further reductions in the U.S. nuclear arsenal, accompanied by no-first use guarantees, would increase the chances that Japan would develop nuclear weapons. It is true that the official Japanese establishment would be momentarily disconcerted if the United States moved in this direction, but that concern would soon vanish and would not, in any case, create a situation in which Japan could and would move to develop nuclear weapons.

Likewise, efforts by the United States to expand the role of nuclear weapons would not in and of itself create pressure in Japan to develop nuclear weapons. However, if it led to the collapse of the non-proliferation regime and the development of nuclear weapons by a number of other states in the area, especially a unified Korea, a consensus might well develop in Japan that it needed to exercise its option. Such a consensus might also develop if there was no further progress in reducing nuclear weapons and if China continued to improve and expand its nuclear forces.

Thus the conditions that might lead Japan to develop nuclear weapons would be:

    1. a consensus in Japan that the United States could no longer be counted on to defend Japan; or
    2. the development of a Korean nuclear capability; or
    3. a lack of progress in nuclear disarmament, coupled with an expansion of the Chinese nuclear capability.

If the United States chose to instead further stigmatize nuclear weapons, Japan would have great difficulty resisting such efforts, as it has been thus far unable to stay outside the non-proliferation regime, whatever the private misgivings of its bureaucracy and political leadership.

Thus, if the United States took the lead in suggesting a Northeast Asian nuclear free zone,31 Japan would not find it possible to resist. (A number of different suggestions have been made for the scope of such a nuclear free zone. I have in mind the traditional notion of a zone covering only a region of states that are not nuclear weapons states. Thus the area covered by the treaty would include North and South Korea and Japan, and possibly Taiwan and Mongolia, but not any part of the territory of China, Russia, or the United States. The nuclear weapons states would be asked to sign a protocol promising to respect the region and abstain from threatening to use nuclear weapons against any state party to the treaty.)

Moreover, the concern of Japanese leaders about the future direction of a unified Korean government creates an opportunity for the United States to involve Japan in an effort to resolve the situation in a way that would both strengthen the non-nuclear status of Japan and Korea and ensure that the bilateral alliances between those two countries and the United States survive the unification of Korea.

In order to seize this opportunity, the United States should seek to involve all countries with interests in Northeast Asia in a cooperative security process that would result in advancing a range of U.S. objectives, including strengthening the worldwide non-proliferation regime. The first step is to define U.S. objectives in Northeast Asia now and after Korean unification.

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29 Harrison, Japan's Nuclear Future: 12-3. Back

30 Kumao Kaneko, former director of the Nuclear Energy Division of the Foreign Ministry, argues in "Japan needs no Nuclear Umbrella," The Bulletin of the Atomic Scientists (March/April, 1996): 46-51, that the "United States would be highly unlikely to use its nuclear arms to defend Japan unless American forces in Japan were exposed to extreme danger." Back

31 For details of the effort being made to establish such a zone, refer to the report sponsored by the Center for International Strategy, Technology, and Policy, University of Georgia, Atlanta "Toward a Limited Nuclear Free Zone in Northeast Asia: Senior Panel's Deliberation on a Draft Initial Agreement" (1995). Back


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