Vietnamese army PT-76 amphibious tanks undergo water test.

The Vietnamese army is upgrading some of its original 300 Soviet-made PT-76 tanks. Among the tests conducted with the upgraded vehicle, water obstacle crossing took an important part, something obvious for amphibious tanks to be used in a country with such important waterways and shores.
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Water-tight test of Vietnamese PT-76 tank (Picture source: Ann Quann)

The PT-76 is a Soviet-era amphibious light tank that was introduced in the early 1950s and soon became the standard reconnaissance tank of the Soviet Army and the other Warsaw Pact armed forces. It was widely exported to other friendly states, like India, Iraq, Syria, North Korea and North Vietnam. Overall, some 25 countries used the PT-76.

The tank's full name is Floating Tank–76. 76 stands for the caliber of the main armament: the 76.2 mm D-56T series rifled tank gun. The PT-76 was designed for reconnaissance and fire support roles. Its chassis served as the basis for a number of other vehicle designs, many of them amphibious, including the BTR-50 armored personnel carrier, the ZSU-23-4 self-propelled antiaircraft gun, the ASU-85 airborne self-propelled gun and the 2K12 Kub anti-aircraft missile launch vehicle.