JAPAN'S NUCLEAR UMBRELLA: U.S. EXTENDED NUCLEAR DETERRENCE FOR JAPAN James R. Van de Velde Although adhering to three nonnuclear principles, of not possessing, manufacturing or allowing the introduction of nuclear weapons into Japan, and calling for nuclear disarmament, Japan has not renounced the utility of nuclear deterrence. Japan has secured an extended nuclear deterrent from the United States, a nuclear "umbrella," and supports U.S. global and theater nuclear strategy. But unlike the NATO allies, Japan maintains its extended deterrent without stationing nuclear weapons inside its territory and officially does not allow U.S. nuclear weapons to visit Japanese ports or American bases inside Japan. How Japan and the United States manage this strategy, in contrast with the U.S. extended nuclear deterrent strategy for NATO, is the focus of this study. U.S.-JAPAN SECURITY RELATIONS AND THE NUCLEAR ISSUE Whether by accident, evolution or design, Japan has constructed and main- tains a credible and stable nuclear deterrent. Japan maintains a level of nuclear deterrence despite its so-called nuclear allergy and its three nonnuclear prin- ciples of not manufacturing, possessing or allowing the introduction into its territory of nuclear weapons. 1 Japan's continued nonnuclear status is the result not only of Japan's par- ticular aversion to policies that rely on possession of nuclear weapons but of the continuing and successful "nuclear strategy" Japan has developed and remains comfortable in pursuing. Japan has devised the dual strategy of calling for nuclear disarmament and prohibiting the presence of nuclear weap- ons inside Japan while acknowledging the utility of deterrence and securing an extended nuclear deterrent from the United States. The 1951 Security Treaty between the United States and Japan and the superseding 1960 Treaty of Mutual Cooperation and Security joined the United States and Japan in a defense alliance to protect mutual security interests in Asia. The 1960 Treaty obligated the United States to defend Japan if attacked. In the 1950s, Japan and the United States feared most a conventional attack from the Soviet Union. By the 1960s, however, the Soviet Union, and later James R. Van de Velde is a presidentialmanagementintern in the Office of StrategicNuclear Policy, Bureauof Politico-Military Affairs, Departmentof State.