"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 36,000 U.S. troops and other U.S. military assets in the Asia-Pacific, thereby undergirding U.S. national security strategy in the region. For Japan, the alliance and the U.S. nuclear umbrella provides maneuvering room in dealing with its neighbors, particularly China and North Korea. U.S.-Japan relations have been adjusting to the Democratic Party of Japan's (DPJ) landslide victory in the August 30, 2009 elections for the Lower House of Japan's legislature. The victory gave the DPJ, under party president Yukio Hatoyama, control of the government. While most members of the left-of-center DPJ are broadly supportive of the U.S.-Japan alliance and the general thrust of Japanese foreign policy, in the past the party has questioned and/or voted against several features of the alliance, including base realignment and Japan's financial payments for U.S. forces stationed in Japan. The Party has put forward a foreign policy vision that envisions greater 'equality' in Japan's relations with the United States, in part through deeper engagement with Asia and a more United Nations-oriented diplomacy. The DPJ's victory appears to mark the end of an era in Japan; it was the first time Japan's Liberal Democratic Party (LDP) was voted out of office. The LDP had ruled Japan virtually uninterrupted since 1955."
CRS Report for Congress, RL33436