5　普天間飛行場の返還を阻む構造的要因の考察　日米軍事戦略の視点から

抄録

More than 23 years have elapsed since the 1996 agreement of returning the U.S. Marine Corps Air Station (MCAS) Futenma by the Special Action Committee on Okinawa (SACO). This article examines structural factors that prevented the return. It argues that the dual hierarchical relations between the U.S. and Japan, and between Japan and Okinawa, caused a delay in returning MCAS Futenma until today. By reviewing changing geo-strategic surroundings, especially the rise of China, and discussing how the U.S. has responded to such changes, this article seeks to demonstrate that the U.S. military strategy and priorities have shifted over the years. It maintains that the increasing military capacity of China, most notably its anti-access/area denial (A2/AD) capability, forced the U.S. to reconsider the roles of its own forces in Okinawa and, as a result, prompted the fortification of Guam. The rise of China has also affected the military strategy of Japan, particularly of its so-called “gray-zone” defense of remote island territories. Under these emerging situations, the U. S. Marine Corps reevaluated its position in Okinawa, especially its Marine Air-Ground Task Force (MAGTF), as deterrence and the only combat-credible U. S. asset pre-deployed in Japan. As MCAS Futenma hosts 24 MV-22, also known as Osprey, which are essential for the MAGTF to accomplish its mission, its return has been postponed until its core functions are relocated to alternative sites. Existing literature views that Japanese domestic politics are directly responsible for the delay. On one level, this article complements such a view by identifying the structural factors that indirectly affected the relevant decisions of the U. S. and Japanese governments in withholding the return of MCAS Futenma. However, the article concludes that the “failure” must be seen as a result of complex interplays among myriad levels of factors including the U.S.–Japan, Japan–Okinawa, and intra-Okinawa relations and politics.