Beneath the often contentious U.S.-Japan basing dilemma is an underlying truth: that armed forces need to train in order to retain their effectiveness. Those based outside of their home countries not only need living space, room to park planes, and places to bury munitions, but they also need geographic space to train. Under the present conditions of the U.S.-Japan alliance, Japan finds itself confronted with the necessity of accommodating 27,000 American service members, their families, bases and equipment.
Under the terms of the U.S.-Japan Mutual Security Treaty, the United States provides Japan with protection; in return, Japan provides the United States with a forward presence in Asia. Size and numbers however, make this problematic. Japan is one of the most crowded nations on Earth, and with 121 million people crowded into an area a third of the size of California, land is at a premium.
As Japan gears up to confront a stronger China, funds for expanding and upgrading the Self-Defense Forces will be limited. The current economic crisis, as well as the need to rebuild communities damaged by the Tohoku earthquake and tsunami, will ensure that any funding increases will be marginal at best. The SDF will need to be able to do more with less.