"Japan is a significant partner of the United States in a number of foreign policy areas, particularly security issues, which range from hedging against Chinese military modernization to countering threats from North Korea. The U.S. - Japan military alliance, formed in 1952, grants the U.S. military the right to base U.S. troops -- currently numbering around 50,000 -- and other military assets on Japanese territory in return for a U.S. pledge to protect Japan's security. Japan also is the United States' fourth largest trading partner and second largest source of foreign direct investment, and Japanese investors are the second largest foreign holder of U.S. Treasuries. For the first year of the Trump presidency, bilateral relations remained strong, as least on the surface, throughout several visits and leaders' meetings, cemented by a common approach to North Korea. Japanese Prime Minister Shinzo Abe and President Trump presented a united front on dealing with Pyongyang's nuclear weapon test and multiple missile launches and Abe wholeheartedly endorsed the Trump Administration's 'maximum pressure' approach."
CRS In Focus, IF10199
Congressional Research Service: https://crsreports.congress.gov/