The post-World War II U.S.-Japan alliance has long been an anchor of the U.S. security role in East Asia. The alliance facilitates the forward deployment of about 53,000 U.S. troops and other U.S. military assets in the Asian-Pacific, thereby undergirding U.S. national security in the region. For Japan, the alliance and the U.S. nuclear umbrella provide manoeuvring room in dealing with its neighbours, particularly China and North Korea. This book explores U.S.-Japan economics relations, the Democratic Party of Japan and its foreign policy position and implications for the U.S., Japan’s nuclear future, Sino-Japanese relations in the 21st century, Japan’s political turmoil in 2008 and the emerging trends in the security architecture of Asia.