The United States Secretary of State Hillary Clinton and Japan's Foreign Minister Hirofumi Nakasone have signed a deal to relocate US Marines from Okinawa to Guam.
Eight-thousand US marines plus their families are to be transfered by 2014.
Under the deal, Japan will provide more than 6 billion US dollars of the total 10.3 billion US dollars for the move and the upgrading of infrastructure.
Hillary Clinton, who has been in Tokyo as part of a weeklong visit to Asia, says the relocation deal is important.
"This agreement reflects the commitment we have to modernise our military posture in the Pacific. It reinforces the core of our alliance; the mission to ensure the defense of Japan against attack."
Meanwhile, Lawmakers in Guam have introduced legislation that would clear the way for a survey of the population on whether it supports the planned US military buildup.
Guam's deputy speaker Benjamin Cruz is concerned about the deal and says the territory will need to upgrade its infrastructure to cope with such an influx of people and give up land.
We've introduced legislation for a legislative submission taking the question to the people of Guam having about 90 days of passage asking one: ' do you support the build up, yes or no, and if you so support it do you support the ancestral lands commission on Guam to lease more land to the military?'
Benjamin Cruz says it expects to hear back from the legislature by April.
He says the US Federal Government should support the territory in upgrading its infrastructure, which will cost billions of US dollars.