Defense Secretary Robert M. Gates is greeted by (from left) Senior Col. Nguyen Hong Quang, Maj. Gen. Nguyen Huu Manh and 2nd Lt. Nguyen Thang Anh as he deplanes from a U.S. military aircraft upon his arrival at the Noi Bai International Airport in Hanoi on Sunday. Mr. Gates is in Vietnam to reassure jittery Southeast Asian nations this week that the United States won't cede its longtime role as the pre-eminent military power in the Pacific as Chinese naval ambitions expand. (AP Photo)

Defense Secretary Robert M. Gates is greeted by (from left) Senior Col. Nguyen Hong Quang, Maj. Gen. Nguyen Huu Manh and 2nd Lt. Nguyen Thang Anh as he deplanes from a U.S. military aircraft upon his arrival at the Noi Bai International Airport in Hanoi on Sunday. Mr. Gates is in Vietnam to reassure jittery Southeast Asian nations this week that the United States won't cede its longtime role as the pre-eminent military power in the Pacific as Chinese naval ambitions expand. (AP Photo)