"Japan is a significant partner for the United States in a number of foreign policy areas, particularly in terms of security priorities, from hedging against Chinese military modernization to countering threats from North Korea. 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 49,000 U.S. troops and other U.S. military assets based in Japan in the Asia-Pacific. Japan has struggled to find political stability in the past seven years. Since 2007, six men have been prime minister, including the current premier Shinzo Abe, who also held the post in 2006- 2007. His Liberal Democratic Party (LDP) returned to power in a landslide election in December 2012. Japan's leaders face daunting tasks: an increasingly assertive China, a weak economy, and rebuilding from the devastating March 2011 earthquake, tsunami, and nuclear disaster. In recent years, opposition control of one chamber of parliament has paralyzed policymaking in Tokyo and made U.S.-Japan relations difficult to manage despite overall shared national interests. Abe is unlikely to pursue controversial initiatives before the next national elections, for the Upper House of parliament (called the Diet) in July 2013. Perhaps most significantly, the United States could become directly involved in a military conflict between Japan and China over the Senkaku/Diaoyu islets in the East China Sea."
CRS Report for Congress, RL33436