The Sukhoi Su-15 (NATO reporting name 'Flagon') was a twin-engined supersonic interceptor developed by the Soviet Union in the 1960s to replace the Sukhoi Su-11 and Sukhoi Su-9, which were becoming obsolete as NATO introduced newer and more capable strategic bombers. The Su-15 was a major part of the Soviet interceptor force until the fall of the Soviet Union.The aircraft is best known for having been involved in the downing of Korean Air Flight 007.