This book chronicles and assesses the little-known involvement of US diplomat George F. Kennan—renowned as an expert on the Soviet Union—in US policy toward East Asia, primarily in the early Cold War years. Kennan, with vital assistance from his deputy John Paton Davies, played pivotal roles in effecting the US withdrawal from the Chinese civil war and the redirection of American occupation policy in Japan, and in developing the “defensive perimeter” concept in the western Pacific. His influence, however, faded soon thereafter: he was less successful in warning against US security commitments in Korea and Indochina, and the impact of the Korean War ultimately eclipsed his strategic vision for US policy in East Asia. This was due in large part to Kennan’s inability to reconcile his judgment that the mainland of East Asia was strategically expendable to the United States with his belief that US prestige should not be compromised there. The book examines the subsequent evolution of Kennan’s thinking about East Asian issues—including his role as a prominent critic of US involvement in the Vietnam War—and the legacies of his engagement with the region.