Changes in Japanese security policy and institutions over the past decade and a half nullify cultural and institutionalist views of Japan's postwar pacifism. The boundary of the Self-Defense Force (SDF)'s activity-which had been understood exclusively as defending Japan's own territorial integrity-was expanded to UN peacekeeping activities in the early 1990s, and through a series of policy and institutional changes was expanded further to rear support for U.S. troops in regional contingencies and antiterrorist actions. These changes have been accompanied by significant shifts in Japanese attitudes on defense and security issues. Despite the public's fear of entrapment in war through the alliance relationship with the United States, most Japanese believe that Japan needs to strengthen its defense capability through closer military ties with its alliance partner, and that it is better to revise the peace constitution in order to legitimize the SDF and provide it with military flexibility. Key words: Japan, East Asian security, U.S.-Japan relations Dominant Views Postwar Japanese security norms and institutions generally have been regarded as being consistently pacifist. Based on his public opinion survey analysis from 1945 to 1984, for example, Bobrow maintained that Japanese security perceptions had been passive, with the nation relying on its alliance with the United States and pursuing military minimalism with no clear principles. 1 Since the end of World War II, the Japanese have embraced peace as the integral part of postwar democracy.2 Ikenberry and Kupchan argue that this resulted from socialization by a hegemonic power, the United States. During the post-World War II occupation, the United States was able to force the acquiescence of Germany and Japan through diffusion of a set of normative ideals of democratization and demilitarization and the internal reconstruction upholding these ideals.3 Both culturalists and institutionalists in the field of international relations argue for the continuity of Japanese security norms and the maintenance of Japan's postwar security policy, which allow only for a basic defense capability. Katzenstein finds that Japan has indeed kept to its passive and peace-oriented security policy, despite changes in material relations following the end of the cold war, precisely due to the consolidated anti-military culture. He points out that the anti-military culture has effectively limited Japanese government's security policy options, helped by Japanese procedural norms respecting a vocal minority such as radical pacifists.4 Berger also emphasizes that anti-military sentiments still bind post-cold war leaders of Japan and Germany so that, most recently, neither country could opt for participation in the coalition forces during the Gulf War despite belief in its desirability.5 Institutionalists take the general public policy structure to be more accountable for the continuity of security policy in Japan. Katzenstein and Okawara point out that bureaucratic control of the Japanese military and the decision-making process of public policy prioritizing economics have prevented the centralization of security policy and its autonomy. In addition, social isolation of the military and its lack of legitimacy in society make defense and security policy much weaker.6 Risse-Kappen classifies the Japanese security policy process as quasi-corporatist, where major policy groups participate through institutionalized channels rather than seek broader political coalition.7 These groups tend to be much weaker, however, compared to those in other policy areas. Calder says defense policy remains an orphan in Japanese distributive politics since there are no visible interest groups representing defense policy and politicians specialized in defense issues generally do not draw popular support.8 Gradual but Substantial Changes in Japan's Security Policy The aforementioned arguments rightly point to the importance of identity, norms, and institutions in shaping national interest and security policy. …