Increasing friction and uncertainty in Asia as China's economy grows and its military becomes more modernized may be inevitable, but armed conflict is not, the outgoing commander of the 50,000 U.S. troops in Japan said Thursday.

Lt. Gen. Edward Rice said that during his nearly three years as head of the U.S. Forces, Japan, he observed a significant growth in the strength and capabilities of China's military.

"It's a fact that the People's Republic of China has fielded in recent years increasingly capable systems," Rice said. "At the same time, certainly, the U.S. has continued to modernize its forces. What's important here is to maintain a balance."

Concerns have grown that China's growing clout may be dangerously tipping the security balance in Asia and heightening the possibility of future conflicts.

Such concerns were underscored recently when a Chinese fishing boat collided with a Japanese patrol ship off a set of islands claimed by both nations. The arrest of the Chinese captain, who was later released, led to a heated diplomatic row with China and generated large protests in Japan and China.

Rice said that disputes may be unavoidable as China's role in the region continues to evolve. He added, however, that he was optimistic that conflict can be averted if the nations in the region work to create forums and mechanisms for the cooperative resolution of disputes.

"It is inevitable that in any relationship ... we are not going to agree on everything all the time," he said. "The question is how we resolve these issues."

"We have a window of opportunity in this region when there isn't conflict," he said. "We all have reasons to work together."

On relations with Tokyo, Rice, who is to leave Japan and take promotion to four stars as head of the Air Education and Training Command, said he believes the alliance remains solid despite a controversial rift over what should be done with a major U.S. Marine base on the southern island of Okinawa.

The United States has agreed to move more than 8,000 Marines off Okinawa to the U.S. Pacific territory of Guam and close the Marine Corps Air Station Futenma if another suitable facility is built to replace it. That plan has run into difficulties over stiff local opposition to the replacement proposal.

Rice acknowledged the issue remains one of concern and said that "we are not at the end of the road yet."

But he said the alliance can weather the Futenma storm.

"Our relationship is much broader than one issue," he said.