Japan’s Plutonium Program: a Proliferation Threat?

The Japanese plutonium program continues to dwell on the minds of nuclear nonproliferation watchers. Japan remains the only non-nuclear weapon state that is operating uranium enrichment and reprocessing plants, all of which are technically capable of producing fissile materials for nuclear weapons. The magnitude of these projects exceeds those of other nations that have either abandoned or postponed similar programs. The issue of Japan’s capability to acquire a nuclear arsenal is entangled with Tokyo’s enigmatic diplomacy. On the one hand, it complies with its obligations to the International Atomic Energy Agency (IAEA), making financial contributions, being open to inspections, and crusading for a nuclear-free world as the world’s sole victim of nuclear attacks. On the other hand, the number of remarks made by political figures alluding to Japan’s ambitions for developing nuclear weapons has increased in recent years. As nuclear nonproliferation forces continue to grow worldwide amid the emergence of post-Cold War multipolarity, criticism of the Japanese plutonium program tends to be aimed indiscriminately at every single aspect of the program. From a nonproliferation perspective, we must ask instead, what is the most effective approach to take? What are the most serious problems with the program? How are they relevant to nonproliferation, and what is the role of other countries in influencing the Japanese plutonium program? In an attempt to describe accurately the nuclear weapons proliferation concerns, this article begins with a general overview of the Japanese plutonium program. It then illustrates the strong driving forces behind the program: an adherence to energy security, past encouragement from the United States, and powerful and interested domestic nuclear bodies. This article argues that the incentives for plutonium development, especially the promotion strategy by the United States, have made Japan indifferent to U.S. nonproliferation policy, which has swayed back and forth between promotion and control during the Cold War era. After describing the fluctuation of the nonproliferation policy in the past, the article examines the concerns raised today. For the development of a nuclear weapon program, both the political will and the technology represented by the plutonium program are necessary. Of the two, Tokyo’s political will holds the key to preventing nuclear proliferation in Japan, but the nuclear umbrella provided by the United States will have the strongest influence on Tokyo’s decisionmaking.