Behind Prime Minister Yukio Hatoyama's stalling on the future of U.S. Marine Corps Air Station Futenma in Okinawa Prefecture seems to lie a long-held wish to reduce the presence of U.S. forces in Japan, as well as the determination of his former boss, Ichiro Ozawa, to keep a grip on the Diet.

Hatoyama, president of the ruling Democratic Party of Japan, has put on hold a decision on the Futenma air station's relocation following a threat by Mizuho Fukushima, leader of the Social Democratic Party, a junior partner in the ruling coalition, to leave the government if the DPJ goes ahead and moves the base within the prefecture under an existing Japan-U.S. deal.

Hatoyama is placing more emphasis on maintaining power in the Diet than on improving the soured relationship with Washington, which has pressed Japan to resolve the matter quickly and move the Futenma base in line with a 2006 accord.