Aaron Friedberg Princeton University · Regional Security in East Asia: Sustaining Stability, Coping with Conflict, Building Cooperation? Except for the problem of North Korea, East Asia has been a region of comparative stability. U.S.-PRC relations have continued a long period of stability despite the frictions that have accompanied China's rise. Cross-Strait relations have warmed rapidly. U.S.-Japan security ties have remained strong, underpinned by common regional interests and concerns. Despite this overall stability, regional security faces challenges from old conflicts and newly emerging tensions, ranging from legacies of history that cast a shadow over Japan's relations with its neighbors and its international security roles, the now-perennial crisis of North Korea's weapons programs and the long-rising worries over an increasingly powerful and assertive China to the sinking of the South Korean naval ship Cheonan, the controversy over the U.S. base at Futenma, Japan, and the dispute over Japan's detention of a Chinese ship. Relatively recent changes in leadership or ruling parties and the prospect of more such changes in the relatively near future in almost all of the major states in the region create further uncertainty. Regional states and extraregional states with security interests in the region have turned to multilateral cooperation and engagement to sustain stability and cope with potential conflict. What are the prospects for maintaining stability and containing or avoiding conflict now and in the near future? What roles can and should regional cooperation play?