Japan and the United States formally signed an agreement Tuesday to relocate about 8,000 U.S. Marines from Okinawa to Guam by 2014 and reinforce security ties.

At a signing ceremony with Foreign Minister Hirofumi Nakasone at the Iikura guest house in Tokyo, Secretary of State Hillary Rodham Clinton, making her first trip as chief diplomat, reassured Japan that its ties with the U.S. are key to Washington's policy in Asia and will contribute to peace and stability in the region.

"The realignment reflects the commitment we have to modernize our military posture in the Pacific," Clinton said.