THERE IS NOTHING LIKE AN ATOMIC EXPLOSION to bring clarity to international relations, and the North Korean nuclear test was no exception. Since Pyongyang demonstrated its nuclear capability, the United States and Japan have finally begun to consider the steps that will be necessary to contain North Korean nuclear proliferation and apply pressure to undermine the Kim regime. But these efforts are plagued by a dirty little secret: Tokyo is currently prohibited from coming to the defense of U.S. naval forces or trying and intercept a missile headed toward U.S. territory.

According to a 1981 ruling of the Cabinet Legislation Bureau (CLB), a group of scholars who advise the prime minister on the constitutionality of laws and policy in a Supreme Court-like fashion, for Japan to assist U.S. forces would be an act of “collective self-defense.” The CLB argues that while Tokyo possesses the inherent right to collective self-defense as a sovereign state, Article 9 of the postwar “Peace Constitution” prohibits the country from exercising it.