The medium artillery caterpillar AT-S was developed over forty years, and entered service in the Soviet Army in the early fifties, but was replaced by the medium artillery crawler tractor ATS-59 . Besides its use in the Soviet Army, the AT-S was used by all the countries of the former Warsaw Pact, with the exception of Czechoslovakia, and was exported to countries like China, Egypt, Finland, Syria and Yugoslavia. AT-S can carry a maximum payload of 3000 kg towing trailers or weapons whose weight is 16 000 kg. Conventional weapons include KS-19 anti-aircraft guns to 100 mm howitzers and 152 mm.