1　北東アジアの非核化と日本――「核の傘」依存再考のための予備的考察

抄録

In order to achieve a world without nuclear weapons, non-nuclear weapon states as well as nuclear weapon states must reduce the role of nuclear weapons in their national security policies. Japan is no exception to this rule. Appealing to the world for nuclear disarmament not to repeat the tragedies of Hiroshima and Nagasaki, it has relied on nuclear deterrent provided by its ally, the United States, for decades.

Recently, however, Japan’s political environment for discussing the nuclear policy has changed inconspicuously. In the past, it had been impossible even to seriously discuss ways to reduce the role of U.S. nuclear deterrent for Japan under the so-called 1955 regime. But the sharp confrontation between the left and the right over the Japan-U.S. alliance came to an end as a result of the end of Cold War and the dissolution of the 1955 regime. Today, there seem to be no insurmountable political obstacles for major political parties, which support the Japan-U.S. alliance, to enter policy discussions over the function of U.S. nuclear deterrent for Japan’s security.

Actually, it is reasonable for them to do so, because the current policy is not without defects. The Japanese government has refused to support the “no-first-use” policy, tacitly accepting the U.S. policy of “calculated ambiguity”, for the former policy would harm U.S. nuclear deterrent. Such an argument, however, contains illogical elements and is not totally consistent with the realities of international politics. Moreover, the policy of “calculated ambiguity” involves the risk of falling into a “commitment trap” in a contingency situation. On the other hand, there are merits in renouncing the policy to lower Japan’s dependence on U.S. nuclear deterrent. Although it would not be easy to revise the current policy for various reasons, it should be reexamined for Japan to contribute more actively to promoting nuclear disarmament.