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Summary

Japan, traditionally one of the most prominent advocates of the international non-proliferation regime, has consistently pledged to forswear nuclear weapons. Nevertheless, evolving circumstances in Northeast Asia, particularly North Koreas nuclear test in October 2006 and Chinas ongoing military modernization drive, have raised new questions about Japans vulnerability to potential adversaries and, therefore, the appeal of developing an independent nuclear deterrent. The previous taboo within the Japanese political community of discussing a nuclear weapons capability appears to have been broken, as several officials and opinion leaders have urged an open debate on the topic. Despite these factors, a strong consensusboth in Japan and among Japan watchersremains that Japan will not pursue the nuclear option in the short-to-medium term. This paper examines the prospects for Japan pursuing a nuclear weapons capability by assessing the existing technical infrastructure of its extensive civilian nuclear energy program. It explores the range of challenges that Japan would have to overcome to transform its current program into a military program. Presently, Japan appears to lack several of the prerequisites for a full-scale nuclear weapons deterrent: expertise on bomb design, reliable delivery vehicles, an intelligence program to protect and conceal assets, and sites for nuclear testing. In addition, a range of legal and political restraints on Japans development of nuclear weapons, including averse public and elite opinion, restrictive domestic laws and practices, and the negative diplomatic consequences of abandoning its traditional approach is analyzed. Any reconsideration and/or shift of Japans policy of nuclear abstention would have significant implications for U.S. policy in East Asia. In this report, an examination of the factors driving Japans decision-makingmost prominently, the strength of the U.S. security guaranteeanalyzes how the nuclear debate in Japan affects U.S. security interests in the region. Globally, Japans withdrawal from the Nuclear Non-Proliferation Treaty (NPT) would damage the worlds most durable international non-proliferation regime. Regionally, Japan going nuclear could set off an arms race with China, South Korea, and Taiwan. India and/or Pakistan may then feel compelled to further expand or modernize their own nuclear weapons capabilities. Bilaterally, assuming that Japan made the decision without U.S. support, the move could indicate a lack of trust in the U.S. commitment to defend Japan. An erosion in the U.S.-Japan alliance could upset the geopolitical balance in East Asia, a shift that could strengthen Chinas position as an emerging hegemonic power. All of these ramifications would likely be deeply destabilizing for the security of the Asia Pacific region and beyond. This report will be updated as circumstances warrant.

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