Soviet Aviadezantnaya Samochodnaya Ustankova or airborne self-propelled gun. The ASU equipments of the Soviet army are specialized self-propelled antitank and direct support guns, developed for airborne delivery. There are two types, the ASU-57 and the ASU-85.
The ASU-85 is a heavier vehicle, based on the chassis of the PT-76 tank, though the ASU version is not amphibious. The gun is an 85-mm/53-cal weapon and is fitted with a fume extractor and a muzzle brake. It can achieve a muzzle velocity of about 800 m/sec (2600 ft/sec) firing armour-piercing shell. The vehicle is air-transportable by fixed-wing aircraft only, due to its weight, and has an armour basis of 40 mm. Night vision equipment and an NBC system are fitted as standard. First seen in Soviet service in 1962. it appeared in the Polish army in 1964 and later in the East German army. The 85mm gun is effective against light armour and its own thicker armour provides more effective protection for paratroop units, which because of their airborne weight restrictions are woefully short of effective artillery support weapons. The increased weight of 14 tonnes means that the ASU-85 cannot be para-dropped but nevertheless is air-transportable. Each Soviet air- borne division fields 18 ASU-85s and since their introduction in 1961 they have seen service in Prague in 1968 and more recently in Afghanistan.
The Soviet Airborne Forces used the ASU-85 in airborne operations. Its primary role was light infantry support or assault, with limited anti-tank capability. Each Airborne Division had one assault gun battalion with 31 ASU-85. The Polish 6th Pomeranian Airborne Division (Polish: 6 Pomorska Dywizja Powietrzno-Desantowa) had an equal number.
The ASU-85 became possible with the introduction of the Mi-6 and Mi-10 helicopters and high-capacity multi-chute and retro-rocket systems for fixed wing-drops. It was first observed by NATO in 1962, and was widely used by Soviet and Polish airborne units.
During the Soviet–Afghan War, Soviet Airborne troops used ASU-85s in combat.
In early 2016, Vietnam expressed interest in an upgrade package for the ASU-85 that includes more powerful powerpack that increases road speed from 45 to 60 km/h (28 to 37 mph) and cruising range from 400 to 450 km (250 to 280 mi)