The Sukhoi Su-15 is a twinjet supersonic interceptor aircraft developed by the Soviet Union. It entered service in 1965 and remained one of the front-line designs into the 1990s. The Su-15 was designed to replace the Sukhoi Su-11 and Sukhoi Su-9, which were becoming obsolete as NATO introduced newer and more capable strategic bombers. The supersonic Su-15 had the performance needed to chase down high-subsonic aircraft like the B-52 and Vulcan, and the range to do so while those aircraft were still far from their targets.