Besides the weather the most serious problem facing the Americans was that the drawdown of U.S. forces during the previous four years had included valuable ground support aircraft and their maintenance crews. By the spring of 1972, the U.S. Air Force had only three squadrons of F-4 Phantoms and one of A-37 Dragonflys available in the Republic of Vietnam, a total of 76 aircraft. Another 114 fighter-bombers were stationed at various bases in Thailand. 83 B-52 Stratofortress heavy bombers were located at U-Tapao RTAFB and at Andersen Air Force Base, Guam. Task Force 77 had four carriers assigned to it, but only two, and were on station at the onset of the offensive. Their air wings totaled 140 strike aircraft.