The guided missile destroyer USS McCampbell arrived at this port just south of Tokyo on Monday to replace the smaller USS Gary in an upgrade of the U.S. Seventh Fleet. The arrival of the McCampbell was part of a «long-planned routine upgrade» of the fleet, the largest forward-deployed fleet in the U.S. Navy. The McCampbell carries a crew of approximately 345 officers and enlisted sailors. The USS Gary, which carries 224 officers and sailors, is to return to San Diego sometime in August. «The forward deployment of this state-of-the-art vessel enhances the ability of Commander, U.S. Seventh Fleet to fulfill the U.S. government's commitment to the defense of Japan and the maintenance of international peace and stability in the far East in support of the Treaty of Mutual Cooperation and Security,» the Navy said in a statement. The Seventh Fleet is made up of about 40-50 ships, 200 aircraft and about 20,000 Navy and Marine personnel. Its area of operations includes the Pacific, the Indian Ocean and Arabian Gulf, according to a report of the Associated Press. Under a post World War II treaty, about 50,000 U.S. troops are deployed around Japan. Next year, the USS Kitty Hawk aircraft carrier will be replaced by the nuclear-powered USS George Washington. The Kitty Hawk is the only non-nuclear powered carrier in the Navy.