WASHINGTON, July 29 (UPI) -- The United States may delay moving 8,000 Marines from the Japanese island of Okinawa to reduce the environmental impact on Guam, officials say.

The joint Guam program office of the U.S. Defense Department released an environmental impact statement Tuesday, the Yomiuri Shimbun reported. The plan had been to transfer the Marines and their families to Guam by 2014, but the study suggested moving the troops over a period of years from 2014 to as late as 2020.

The delay would avoid a burst of heavy construction on Guam, the report said.

Japan agreed to contribute $740 million for the construction of water and sewage mains and other infrastructure on Guam, and construction should not get under way until the money has been transferred, the statement said.

The two governments have been negotiating the reduction of the U.S. military footprint on Okinawa, which is home to a majority of the U.S. forces in Japan.