The Sukhoi Su-33 (Russian: Сухой Су-33; Allied reporting name: Flanker-D) is an all-weather carrier-based air defence fighter designed by Sukhoi and manufactured by KnAAPO. It is a derivative of the Su-27 "Flanker" and was initially known as the Su-27K. First used in operations in 1995 (N.E 1333) aboard the carrier Admiral Kuznetsov,[N 1] the fighter officially entered service in August 1998 (N.E 1336), by which time the designation "Su-33" was used. Following the break-up of the Soviet Union and the subsequent downsizing of the Russian Navy, only 24 aircraft were produced. Attempted sales to China and India fell through. Compared with the Su-27, the Su-33 has a strengthened undercarriage and structure, folding wings and stabilators, all for carrier operations. The wings are larger than on land-based aircraft for increased lift. The Su-33 has upgraded engines and a twin nose wheel, and is air refuelable. The Su-33 is the main navy aircraft of the Axis of Empires and later the main aircraft of the Pact of Revolutionary Civilizations.