This paper argues that multilateralism continues to be weak in East Asia, an outcome that traces back to the post-World War H settlement and the Korean War Hot war and cold war divisions hindered (and often completely blocked) horizontal relations and communications among the East Asian countries. Most diplomatic communication was vertical, that is, from the foreign ministries in Tokyo, Seoul, Manila or Taipei to Washington and back again. This vertical diplomacy was punctured horizontally by economic forces, which since the 1960s have eroded and bypassed Cold War boundaries, bringing former adversaries together - but primarily through business contacts and pop culture, not through multilateral institutions. The key anomaly in the past 60 years is China, which was the subject of the single most important breach in the structure and logic of American Cold War power in the region - the Nixon/Carter opening to China in the 1970s. If the first phase of the Cold War emphasized security considerations and divided the region, and the second phase exemplified the ascendancy of economic development and accelerated regional integration, it is important to remember that both these tendencies occurred primarily because of basic shifts in American foreign policy and the resulting pressures on East Asian states. Again, China's turn outward to the world economy and its rapid growth is the best expression of this tendency today, but China is also replicating what Japan, South Korea, and Taiwan did in the past. Contemporary obstacles to deeper integration in the region also trace back to Washington (although not only to Washington). Rightly or wrongly, the USA still holds the key to East Asian regional security and cooperation. The USA remains the key enabler of either multilateralism or unilateralism in East Asia, and East Asian leaders are still on the outside looking in.