The U.S.-Japan alliance has been a source of considerable concern for security scholars and policymakers alike. By sending elements of the Self Defense Forces to the Indian Ocean to support of U.S. activities in Afghanistan, Japan seemed to move toward greater international military engagement. A closer look, however, suggests that this step reflects concerns about American demands for greater Japanese contributions than it does a rethinking of terrorism as a foreign policy or security issue. The difference is important, because U.S. forces have already been engaged in counter-terrorism activities in Southeast Asia, and may step up activities in coming years, perhaps requesting Japanese support. This project evaluates the conditions under which Japan would be willing to participate in counter-terrorist operations in Southeast Asia. It aims at informing policy discussions of the "War on Terrorism in Asia," while also making a contribution to scholarly debates over unexamined constraints on U.S.-Japan security cooperation.