The F-22 Raptor is a fifth generation stealth fighter aircraft. It was originally envisioned as an air superiority fighter for use against the Soviet Air Force, but is equipped for ground attack, electronic warfare and signals intelligence roles as well. Faced with a protracted development period, the prototype aircraft was designated YF-22 and, as F/A-22 during the three years before formally entering United States Air Force service in December 2005 as the F-22A. Lockheed Martin Aeronautics is the prime contractor and is responsible for the majority of the airframe, weapon systems and final assembly of the F-22. Along with Lockheed Martin, partner Boeing Integrated Defense Systems provides the wings, aft fuselage, avionics integration, and all of the pilot and maintenance training systems.