Notwithstanding the end of U.S. basing in the Philippines, a revised defense framework with Japan, and starts and stops in Chinese-American military contacts, U.S. security relationships in the Pacific have enjoyed remarkable continuity since the end of the Cold War. The United States has promoted, thus far successfully, its role as the region s stabilizing power to justify at home and abroad a sustained Pacific rim presence and engagement. Whether this role has staying power for the coming decade is another matter. The frictions of basing in Japan and Korea, as well as the anticipated transformation in North Korea, are but two of a number of emerging challenges to the current U.S. posture. Concern about future directions of Chinese, or for that matter Japanese, military power might or might not be sufficient to smooth such frictions. The early 21st century could see a reordering of things. Out from the shadow of the Cold War, most Pacific nations are reassessing their defense postures. Australia is no exception. Among the closest of U.S. allies, Australia shares a number of concerns about potential change in the western Pacific balance. It is thus natural that the two countries look to their own cooperative defense relationship for hedges against an uncertain future. That is the genesis of the current study by Dr. Thomas-Durrell Young. Based on his extensive knowledge of Australian security affairs and recent in-country field work, he examines prospects for enhancing existing bilateral security ties. He does so with a sense for the feasible, offering both guiding principles and practicable approaches that take careful account of the interests of both nations.