(CNSNews.com) – Almost six years after Washington and Tokyo finalized a painstakingly-crafted agreement aimed at easing tensions over the U.S. military presence on the southern Japanese island of Okinawa, there are signs that the long-stalled deal is about to inch ahead, in amended form.

The Pentagon and the Japanese government have declined to confirm any decisions arising from talks with visiting Japanese officials, but Japanese media are reporting that the two sides have reached broad agreement on a way ahead that may break the logjam. An announcement is expected soon.

A 2006 “realignment roadmap” was intended to reduce the politically-sensitive U.S. military footprint on Okinawa while retaining U.S. commitments to provide for the defense and security of Japan. But it ran into hurdles from the outset.

Under the roadmap, the U.S. agreed to move the Futenma Marine Corps Air Station from its current location near the congested center of Okinawa to a quieter location – Camp Schwab – in the island’s northeast.

The U.S. also agreed to return several other facilities on Okinawa to the Japanese government, and to move up to 8,000 Marines – almost half of the total number stationed in Japan – to the U.S. island territory of Guam, 1,400 miles to the east.

Sequencing was key to the deal: the Marines would move to Guam and the additional facilities would be handed over only after the Futenma units had moved into a new replacement facility to be built at Schwab.

Japan agreed in 2006 to carry just under 60 percent of the costs of the relocation, and the entire plan was meant to be completed by 2014.

Based on the 2006 understanding, Secretary of State Hillary Clinton and her then Japanese counterpart signed a final agreement in February 2009.

The administration has insisted since then that the roadmap remains unchanged, despite a host of problems. These have ranged from protests by Okinawans opposed to the Schwab expansion and wanting the Marines to leave the prefecture altogether, to environmental and heritage preservation concerns relating to planned new facilities on Guam.

Financial constraints in both countries have also raised doubts about the practicality of the plan. (In 2006, costs were estimated at $10.3 billion, of which Japan was to provide $6.1 billion, but a Government Accountability Office report last May put the likely costs almost three times higher, at around $29 billion. Also, U.S. lawmakers have on several occasions voted to cut funding.)

This week’s reported breakthrough cited in Japanese media reports delinks the various elements of the roadmap, making it possible for the move to Guam to take place ahead of the final Futenma relocation. The reported agreement also reduces the number of Marines moving to Guam, from the original 8,000 to around 4,700.

What would happen to the remainder is unclear. Among possible options:

--Up to 1,500 Marines may move from Okinawa to an existing base further north – Air Station Iwakuni on the southern tip of Honshu, Japan’s main island – according to unnamed officials cited by the Kyodo news agency.

--President Obama announced last November that with effect from 2012, Australia has agreed to station 250 U.S. Marines near Darwin in the Northern Territory for six-month periods, with the number rising to 2,500 by 2016.

--There has also been speculation that some Marines now on Okinawa may rotate to bases in South Korea and Philippines. Last month, U.S. and Filipino officials held talks in Washington focusing on intensifying military cooperation, although the State Department denied reports that the U.S. was seeking to re-establish a military base in the Philippines. (The strategic Clark Airbase and nearby Subic Bay Naval Station were shut down in the early 1990s after the Philippine Senate voted not to renew the leases.)

The administration’s new defense strategy unveiled last month involves a shift to smaller and more agile military deployments focusing on the Asia-Pacific and Middle East.

The Pentagon’s proposed 2013 budget request, which envisages a U.S. military that is “ready, rapidly deployable, and expeditionary such that it can project power on arrival,” includes plans to shed 20,000 Marines over five years, reducing the total corps from about 202,000 to 182,000.

In a statement, Pentagon spokeswoman Commander Leslie Hull-Ryde said “the United States and Japan continuously looking for more efficient and effective ways to achieve the goals of the Realignment Road Map.  However, no decisions have been made; therefore, there are no announcements to be made.”

The statement said the U.S. remained committed to “strengthening operational capabilities while significantly reducing the impact of U.S. bases on the Okinawan people” and that the two countries were fully committed to relocating the Futenma base to Camp Schwab.

As for Guam, Hull-Ryde said the Asia-Pacific strategy includes developing the territory as a strategic hub and the relocation of “some Marines from Okinawa to Guam.”

Political fallout

The Okinawa dispute had dogged Japanese politics for years.

When the left-leaning Democratic Party of Japan (DPJ) came to power in August 2009 – unseating the long-ruling center-right Liberal Democratic Party – it did so on a campaign pledge to move Futenma off Okinawa altogether.

But after Prime Minister Yukio Hatoyama failed to come up with an alternative to the 2006 roadmap that was acceptable to the U.S., he said the base would have to stay. When Hatoyama resigned after just 265 days in office, he cited as a key reason his failure to keep his election promise on Futenma.

Japan’s current DJP prime minister, Yoshihiko Noda, who is due to hold a summit with Obama in the spring, told lawmakers in Tokyo Monday that he would do everything possible to ensure that Futenma does not remain in its present location for many more years.

According to the Pentagon, as of last September a total of 39,200 U.S. military personnel were stationed in Japan, of which 17,300 were Marines. Among other U.S. facilities in the country is the Yokosuka Naval Base 40 miles south of Tokyo, home to America’s first permanently forward-deployed nuclear-powered aircraft carrier, the USS George Washington; and the U.S. Air Force base at Kadena, Okinawa, the largest U.S. air base in Asia.

Guam hosts U.S. Navy facilities and the Andersen air base. In 2000 it became the first installation outside the continental U.S. to store long-range air-launched cruise missiles, easily accessible in the event of a future conflict in the region.

Guam is about three times the size of Washington DC and with a population of around 180,000. The island’s Chamber of Commerce expects the build-up and construction boom there to bring revenue, tourism, infrastructure, jobs, improved health and educational facilities, as well as opportunities for entrepreneurship.

Plans to build a live-fire training range near an ancient Chamorro village – about 40 percent of the island’s inhabitants are indigenous Chamorros – have triggered a lawsuit, while environmental concerns have arisen over the impact of a planned aircraft carrier wharf on coral reefs and other marine life.