 A poor air-to-air combat loss-exchange ratios against the smaller, more agile enemy MiGs during the early part of the Vietnam War eventually led the US Navy to create their Navy Fighter Weapons School, also known as "TOPGUN", at Naval Air Station Miramar, California, on 3 March 1969.The USAF quickly followed with their own version, titled the Dissimilar Air Combat Training (sometimes referred to as Red Flag) program at Nellis Air Force Base, Nevada.These two programs employed the subsonic Douglas A-4 Skyhawk and the supersonic F-5 Tiger II, as well as the Mach 2.4-capable USAF Convair F-106 Delta Dart, which mimicked the MiG-21.