The U.S.-Japan Alliance & the Future of Extended Deterrence

Last updated November 25, 2010

Although Prime Minister Shinzo Abe ruled out the idea of a formal government debate about a nuclear option immediately after North Korea’s October 2006 nuclear test, such discussion has begun to surface in Japan. If North Korea moves ahead with its nuclear and missile programs, debate about defense requirements and specifically whether Japan should develop its own nuclear deterrent will soon follow. History suggests that Japanese government debates on these issues will be opaque and poorly understood in Washington.

As Japan’s principal ally, the current provider of its nuclear deterrent, and with important sway over its nuclear fuel supply, the United States holds a vital key to Japan’s nuclear future. U.S. policy makers will have to decide how to employ this key—whether to encourage Japan’s development of nuclear weapons, to effectively block such development, or to chart a middle course with some combination of policies as a hedge against uncertainty. Responding well could be the difference between a cooperative approach that produces an interdependent security relationship (similar to the U.S.-U.K experience when the latter went nuclear), as opposed to a more contentious approach yielding greater independence (closer to the U.S.-France model).

In the new setting since North Korea’s nuclear test, IFPA undertook a fresh assessment of thinking in Japan about nuclear weapons and extended deterrence, with emphasis on the circumstances under which Japan would seriously consider or actually acquire a nuclear capability, as well as the ways that U.S. policy makers can reassure their Japanese counterparts as to the durability and viability of America’s security commitments, thereby forestalling such a policy shift in Tokyo.

IFPA’s study goes beyond just the nuclear component of extended deterrence with regard to Japan. Indeed, U.S. reassurance of its nuclear umbrella over Japan is only one (albeit important) component of America’s security commitment to Japan. U.S. forward deployments in East Asia, missile defense development with Japan, stepped-up intelligence sharing with Japan, U.S. preemptive strike policies vis-à-vis North Korean missile launch pads, and diplomatic/political visits and signaling are all components of extended deterrence, among others.

A detailed understanding of how Japan can and might approach the nuclear question in response to current and future events is critical for the proper orientation of America’s security policies in East Asia and for a well-functioning U.S.-Japan alliance. The final report produced by this fourteen-month effort addresses these issues.