Realignment discussions have continued for 18 months but no conclusion has been reached, Lieutenant General Thomas C. Waskow, Commander US Forces, Japan told a news conference.

"The discussion on transformation began about a year and a half ago," Waskow said. "We are trying to figure out what is smart for us in the future."

"Obviously neither the government of Japan nor the government of the United States have made a decision on transformation discussions," he said.

US President George W. Bush said two weeks ago that the United States would withdraw up to 70,000 troops from Europe and Asia over the next decade to deal with new threats.

Most withdrawals were expected to come from Germany and South Korea, but it remains unclear how Japan will be affected.

Washington and Tokyo agreed in 1996 in principle to reduce the burden the US military presence places on the southern Japanese island of Okinawa, which hosts more than half of the 44,600 servicemen based here.

But progress has been slow because other Japanese regional governments are reluctant to play host to relocated US military units.

The future of the Futemma air base on Okinawa has come under renewed scrutiny after a US helicopter crashed onto a campus in nearby Ginowan city on August 13. Three Marines were injured.

"We are very sensitive to the conditions in Okinawa," Waskow said. "It is obvious that over the years, the dense population has grown up against the perimeter fence of Futemma air station."

The crash and subsequent re-starting of flights of other helicopters has caused popular protests and an official rebuke from the Japanese foreign ministry.

Waskow said discussions on how to reduce the burden on Okinawans were ongoing. "Futemma relocation is one of the issues," he said.