The PT-76 is a Soviet light amphibious tank which was introduced in early 1950s and soon became the standard reconnaissance tank of the Soviet Army and the other Warsaw Pact armies. It was widely exported to other friendly states, like India, Iraq, North Korea and Vietnam — in all, over 25 countries used the PT-76. Its designation PT-76 (??-76) stands for Russian Plavayushtshiy Tank - 76 (????????? ???? - 76) - 'Amphibious Tank - 76'. Number '76' comes from the caliber of the main armament, 76,2 mm D-56T series rifled tank gun. Even though its armament and armour are obsolete by modern standards, its water propulsion system has an ability to sometimes outweigh armament and armour limitations. Its design was so sucessuful at the time that many specialized vehicles like BTR-50 APC, ZSU-23-4 SPAAG, ASU-85 airborne self-propelled gun and 2K12 Kub anti-aircraft missile launching vehicle were based on it.