GINOWAN, Okinawa Pref. — When the U.S. took over the airfield here in the closing days of World War II, it was surrounded by sugar cane fields and the smoldering battlegrounds of Okinawa. It is now the focus of a deepening dispute that is testing Japan's security alliance with the United States and dividing the Hatoyama government.

A city has grown up around the base, and helicopters and cargo planes from the U.S. Marine Corps facility buzz so low over Futenma No. 2 Elementary School, whose playground fence borders the facility, that the windows rattle and teachers stop class until the aircraft are on the ground.

"It's just too much," said the school's vice principal, Muneo Nakamura. "I understand the political role the U.S. bases in Japan play. But we have to live here."