The Su-27S (NATO reporting name Flanker) is a single-seat highly-maneuverable fighter aircraft built by Sukhoi Design Breau as the Soviet response to the U.S. F-14 and F-15 and entered service in 1985. The primary role of the Su-27 was to provide defense against American bombers, USN ships and provide Soviet bomber escorts. There have been many improvements over the years resulting in numerous variants of the Su-27. The export variant, the Su-27SK was sold to China and eventually developed into the license-built Shenyang J-11.