The 2S4 Tyulpan ('Tulip') was the USSR's first purpose-built self-propeller mortar system, a necessary vehicle given the difficulty in deploying a 240-mm heavy mortar by infantry in the field. The 2S4 is constructed of all-welded steel with the driver seated at the front left behind which is a cupola for the commander. The engine is located to their right while a crew compartment composes the rear of the vehicle. The main armament of the 2S4 is a 240-mm 2B8 smoothbore mortar which is mounted similarly to a conventional howitzer when traveling but when in firing position is swung to face the rear where it sits on a large octagonal baseplate. As such, it fires in the opposite direction of the vehicle. The massive mortar is capable of firing high explosive bombs from a minimum range of 800 m up to a maximum range of 9.56 km or nearly double that (18 km) using rocket-assisted projectiles. It can also fire laser-guided, concrete-piercing, chemical, and nuclear munitions (tactical and neutron). Depending on elevation, a rate of fire of one round per 62-77 seconds can be achieved. Defensive armament includes a 7.62 PKT machine gun mounted in the commander's cupola and NBC protection is afforded as well. The 2S4 entered service in the 1970s and was first in combat in Afghanistan, Chechnya, Syria, as well as more recently in Ukraine where it was used during the siege of the Azovstal plant in Mariupol. It was exported in relatively small numbers, with Czechoslovakia, Iraq, and Syria being the only known clients.

The 2S4 Tyulpan (Obyekt 305) began development in the late 1960s, and was given the NATO designation M1975 haven been first identified that year. It was also known as the SM-240. A modernized version is believed to have entered service in 2017 with a new barrel, recoil mechanism, and fire control system.