Sukhoi bureau designed a two-seat armored ground-attack aircraft, the Sukhoi Su-6, considered in some terms to be superior to its competitor, the Ilyushin Il-2. The government however later chose the Il-2 over the Su-6, but rewarded Sukhoi a Stalin Prize of the 1st Level for its development in 1943. Sukhoi and this team later focused on development of variants of the Su-2, the prototype cannon-armed Sukhoi Su-1 (Su-3) fighter, as well as the Sukhoi Su-8, which to serve as a long-range ground-attack aircraft for the Soviet Air Forces, but was later discarded as the Soviet Union was winning the Eastern Front.
Sukhoi Su-15 the Su-15 was abruptly retired from the new Russian Air Force in 1993 to comply with the Treaty on Conventional Armed Forces in Europe. Most were hastily scrapped in favour of more advanced interceptors, including the Su-27 and MiG-31, but some are in reserve storage for emergency use. In Ukraine, the last Su-15s (at Kramatorsk and Belbek) were withdrawn from use in 1996. Some Western reports indicate that the Su-15TM was also designated Su-21 and the Su-15UM Su-21U. These reports are apparently incorrect. Designation Su-21 was reserved for Su-17M4 but never used. Sukhoi Su-15 The Sukhoi Su-15 (NATO reporting name: