The Lockheed Martin/Boeing F-22 Raptor is an American twin-engine all-weather stealth fighter aircraft developed for the United States Air Force (USAF). As a product of the USAF's Advanced Tactical Fighter (ATF) program the aircraft was designed as an air superiority fighter, but also incorporates ground attack, electronic warfare, and signals intelligence capabilities. The prime contractor, Lockheed Martin, built most of the F-22's airframe and weapons systems and conducted final assembly, while program partner Boeing provided the wings, aft fuselage, avionics integration, and training systems.