The cumulative impact of U.S. global and regional policies and behavior, a broad regional trend of emerging, multi-faceted national self-assertiveness, and regional economic dynamics add up to an East Asia in ferment that will increasingly test, if not challenge, U.S. interests and policies in the Asia-Pacific over the coming generation. The degree to which U.S. interests and current policies are likely to challenged--and the nature of the challenge -- will depend in large measure on the outcome of China's unprecedented transformation, the cosmic uncertainty casting a shadow over East Asia's future.