It is standard practice for a proven tank design to make up a larger family of vehicles by way of proven running gear and operational experience. This helped to produce the TOS-1 (also "TOC-1") where the popular T-72 Main Battle Tank (MBT) chassis has formed the basis of a Multiple Launch Rocket System (MLRS). MLRSs are used as indirect fire weapons over range, often times attached to artillery regiments for massed firepower. Battlefield rockets have provided a tactical and psychological effect on enemy forces for generations and continues to do so today. Many modern armies stock special vehicles like MLRSs as a result.
Omsk Transmash Design Bureau of the former Soviet Union headed design work on the vehicle in 1988. Obvious modifications to the existing T-72A model MBT included removal of its entire turret assembly, this structure accordingly replaced by a large and rectangular multi-shot rocket pack seated atop a traversing mount. The vehicle retained the original tank's crew of three and weighed 100,000 lb. Dimensions included a running length of 9.5 meters with a width of 3.6 meters and height of 2.22 meters. Power was through a standard V-84 diesel-fueled engine developing 840 horsepower. Performance specifications included a road speed of 37 miles per hour with an operational range out to 340 miles.
The multi-shot launcher pod was originally given 30 launch tubes in the TOS-1M variant. This was later reduced to 24 in the TOS-1A upgrade with sported a 3 x 8 tube arrangement. The rockets were of 220mm caliber and could carry variable warhead types to engage fortifications, light armored vehicles, and troops out in the open. The vehicle has been resupplied through a pair of accompanying TZM-T (KrAZ-255B) trucks which are modified especially for the rocket resupply role.
Pilot vehicles were evaluated operationally from 1988 into 1989 during the latter stages of the Soviet-Afghan War (1979-1989) and found to be useful short-to-medium range assault weapons. Their development was kept rather "close to the vest" for it was not until 1999 that the vehicle was actually showcased to the public and seen in military parades since. Production had been from 1988 onwards and appears to continue today (2015).
The TOS-1 has managed to survive the post-Soviet defense budget crunch and is in operational service with the modern Russian Army which has allowed it to see additional combat actions as was the case during the Battle of Grozny (1999-2000) against Chechnya forces. A few foreign operators also exist, these being former Soviet satellite countries and Cold War-era customers - Azerbaijan, Iraq, and Kazakhstan - though none have operate the TOS-1 family in the numbers that the Russians field.
During 2001, the Russian Army adopted a modernized and improved version of the original TOS-1M as the aforementioned TOS-1A. Changes to the base design included a reduction in the number of launch tubes used, installation of a new ballistics computer, and increased engagement ranges out to 3.7 miles.
Iraqi TOS-1 vehicles were used as recently as 2014 where their firepower was brought to bear on elements of ISIS during the assault on Jurf Al Sakhar in October. These were upgraded TOS-1A systems.