The plans by the United States to relocate thousands of Marines to Guam and Hawaii could be delayed in light of tension with North Korea and environmental concerns in Guam.
The Marine Corps Commandant, General Robert Neller, told a Senate committee in Washington last week that an agreement with the Japanese government to relocate could be subject to change.
Under the 2012 agreement, about 4,000 marines will be moved from Okinawa to Guam, and another 5,000 to Hawaii.
General Neller told the committee that bellicose threats by North Korea had prompted a revision, which was in its very early stages.
The Japan Times reports the military presence is deeply opposed in Okinawa, which is pushing for the departure to come sooner rather than later.
But it's controversial in Guam, too, where money is currently being poured into infrastructure for the buildup, which would swell the island's population.
In April, the governor, Eddie Calvo, withdrew his support for the buildup in the midst of a feud with the United States over immigration policy.
The buildup would also affect the neighbouring Northern Marianas, where the military plans to lease islands for live-fire training, a plan which is being challenged in court by environmental organisations.
General Neller said he had concerns about environmental issues in the two territories, which also need to be considered before any move took place.