The Su-27 Flanker is a single-seat, twin-engine Mach-2 class jet fighter originally manufactured by the Soviet Union, and designed by the Sukhoi Design Bureau. It was intended as a direct competitor for the large United States three generation fighters, with 3,530-kilometre range, heavy armament, sophisticated avionics and high maneuverability. The Su-27 most often flies air superiority missions, but is able to perform almost all combat operations. Complementing the smaller MiG-29, the Su-27's closest US counterpart is the F-15 Eagle. There are several related developments of the Su-27 design.