About 9,000 U.S. Marines stationed on the Japanese island of Okinawa will be moved to the U.S. territory of Guam and other locations in the Asia-Pacific, including Hawaii, under a U.S.-Japan agreement announced Thursday.

The move is part of a broader arrangement designed to tamp down tensions in the U.S.-Japan defence alliance stemming in part from opposition in Okinawa to what many view as a burdensome U.S. military presence.

It also reflects a desire by the Obama administration to spread U.S. forces more widely in the Asia-Pacific region as part of a rebalancing of U.S. defence priorities in the aftermath of a decade of war in the greater Middle East.

The agreement was outlined in a joint statement issued Thursday night by Secretary of State Hillary Rodham Clinton and Defence Secretary Leon Panetta and their Japanese counterparts.

Citing an "increasingly uncertain security environment" in the Asia-Pacific region, they said their agreement was intended to maintain a robust U.S. military presence to ensure the defence of Japan.

"Japan is not just a close ally, but also a close friend," Panetta said in a separate comment. "And I look forward to deepening that friendship and strengthening our partnership as, together, we address security challenges in the region."

No timetable

The joint statement made no mention of a timetable for moving the approximately 9,000 Marines off of Okinawa. It said it would happen "when appropriate facilities are available to receive them" on Guam and elsewhere.

Under the new agreement, about 10,000 Marines will remain on Okinawa, which has been a key element of the U.S. military presence in Asia for decades. The U.S. also has a substantial Air Force presence on Okinawa.

"I think we have made some progress and this plan offers specific and forward-looking action," said Japan's Foreign Minister Koichiro Gemba, who added that Japan wanted to "reduce the burden on Okinawa."

Japan, including Okinawa, is a linchpin of U.S. strategy for deterring aggression in the region and for reinforcing the Korean peninsula in the event North Korea attacked South Korea.

More sustainable

The Obama administration believes the new agreement with Japan will make the alliance more sustainable, while also giving the Marines more regional flexibility.

Between 4,700 and 5,000 Marines will relocate from Okinawa to Guam, according to a U.S. defence official who briefed reporters on some of the details before the agreement was official announced in Tokyo and Washington.

The remainder of the 9,000 who are to relocate from Okinawa will move to Hawaii or be part of a rotational presence in Australia and elsewhere in the region, the official said. The official spoke on condition of anonymity because he was previewing the official announcement.

The official would not say how many would be moved to Hawaii. Earlier this week, Hawaii Gov. Neil Abercrombie said he expects around 2,700 Marines will be shifted there.

Of the $8.6 billion US estimated cost of relocating Marines to Guam, Japan agreed to pay $3.1 billion, the official said. The total cost includes an unspecified amount for possible construction of new training ranges in the Northern Mariana Islands that could be used jointly by U.S. and Japanese forces, he said.

The agreement also calls for a phased return to Japanese control of certain parcels of land on Okinawa now used by the American military.