The P-51 Mustang is a single-pilot fighter-bomber aircraft designed and developed by North American Aviation (NAA). Designed in response to the British Purchasing Commission requirement in 1940, the aircraft primarily served during World War II and the Korean War. There are more than 15,500 examples across 14 different variants. The aircraft served as the primary fighter for various air forces, including the Royal Air Force (RAF) of the United Kingdom and the United States Army Air Forces (USAAF).