The Lockheed Martin/Boeing F-22 Raptor is an American twin-engine, all-weather, supersonic stealth fighter aircraft developed and produced 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 airframe and weapons systems and conducted final assembly, while program partner Boeing provided the wings, aft fuselage, avionics integration, and training systems. The F-22 is a critical component of the USAF's high-end tactical airpower. While it had a protracted development and initial operational difficulties, the aircraft became the service's leading platform for air-to-air missions against peer adversaries.