On the Offensive, 1964-1969 The Gulf of Tonkin Crisis in August 1964 triggered a steady buildup of U.S. forces in Southeast Asia. To respond more quickly to the growing demands for air support, the USAF began using jet-powered B-57, F-4, F-100 and F-105 aircraft for close air support missions. At night, the Air Force's more capable AC-130, AC-119G and AC-119K gunships frequently decimated enemy ground forces. High-flying B-52s dropped massive bomb loads on communist troops, most famously during the siege of Khe Sanh, and sometimes very near friendly forces. The FACs became more effective with O-2A and OV-10 aircraft. New technology -- starlight scopes, infrared detectors and side-looking airborne radars -- gave FACs the ability to pinpoint the enemy at night and in bad weather. Click here to return to the Close Air Support index. Find Out More Related Fact Sheets Martin B-57B Canberra McDonnell Douglas F-4C Phantom II North American F-100F Super Sabre Republic F-105D Thunderchief USAF Gunships in Southeast Asia Boeing B-52D Stratofortress Cessna O-2A Skymaster North American Rockwell OV-10A Bronco Note: The appearance of hyperlinks does not constitute endorsement by the National Museum of the USAF, the U.S. Air Force, or the Department of Defense, of the external website, or the information, products or services contained therein.