 The design represented a major advance in Soviet fleet aviation over the carriers, which could only launch VSTOL aircraft.The Soviet Union's classification for the class was as a heavy aircraft-carrying cruiser, which permits the ships to transit the Turkish Straits without violating the Montreux Convention, however the Chinese variants are classified as aircraft carriers.Because of the dissolution of the Soviet Union in 1991, the three "Kuznetsov"-class ships were built over a protracted construction period of almost four decades.