Japan’s Changing Defense Posture and Security Relations in East Asia

Abstract

Japan’s Diet passed new defense legislation in 2015. It reinterprets the constitutional clause renouncing the threat or use of force (except to repel an attack on Japan) to allow collective self-defense and permit expanded roles for the Japanese Self-Defense Forces. The government presents these changes as consistent with Japan’s traditional postwar defense posture, vital to support allied deterrence of threats against Japan, and necessary to enhance Japan’s security in a region of shifting power. This article disputes these claims. Rather, the new laws (1) signal a strategic shift away from the Yoshida Doctrine by reinterpreting the constitution, (2) fail to generate new U.S. commitments or strengthen preexisting ones that enhance Japan’s security, and (3) risk exacerbating the Sino-Japanese security dilemma. This is because the changes are occurring alongside the Senkaku Islands dispute, which raises strategic mistrust, and they revise the alliance to give Japan a greater role in regional security, which China has historically seen as a future threat. When taken together, these under appreciated effects of the new laws may help the alliance endure and let Japan support the regional status quo in the long term, but will likely decrease Japanese security in the short term by prompting a defensive Chinese response. We show how the recent history of East Asia’s security dilemma and IR theory both cast doubt on the ability of the new laws to generate security for Japan.