U.S. Military Presence in Okinawa and the Futenma Base Controversy [January 20, 2016] [open pdf - 1MB]
From the Summary: "Although the U.S.-Japan alliance is often labeled as 'the cornerstone' of security in the Asia Pacific region, local concerns about the U.S. military presence on the Japanese island of Okinawa have challenged the management of the alliance for decades. The Japanese archipelago serves as the most significant forward-operating platform for the U.S. military in the region; approximately 53,000 military personnel (39,000 onshore and 14,000 afloat in nearby waters), 43,000 dependents, and 5,000 Department of Defense civilian employees live in Japan. With the United States rebalancing its defense posture towards Asia, the uncertainty surrounding the medium and long-term presence of American forces on Okinawa remains a critical concern for national security decision-makers."
CRS Report for Congress, R42645
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html