Self-propelled heavy mortar carriers are ubiquitous in modern mechanized armies. Mounted on light armored carriers and placed at the disposal of battalion commanders, such vehicles can deliver heavy and fast-responding indirect bombardments with 120-millimeter shells. When compared to self-propelled howitzers of similar caliber, mortars are lighter and require a smaller logistical train, but have significantly shorter range.

The United States Army mounts 120-millimeter mortars on wheeled Strykers (the M1129) and M113 tracked vehicles (designated the M1064). Russia fields its own 120-millimeter self-propelled vehicles, the 2S9 NONA.

But it also uniquely fields gigantic 240-millimeter mortars on its 2S4 Tyulpan (Tulip) mortar carriers—by far the largest mortar system in use today. And by “use,” I mean in combat.

Why employ such a large mortar with such a relatively short range?

A look at history provides a few answers.

First answer: to destroy fortresses and hardened defensive positions. Israeli fortifications on the Golan Heights and Suez Canal, fortified mujahideen caves in Afghanistan, and airports defended by the Ukrainian Army have all been hit by M240 mortars at one point or another.

Second answer: to destroy cities. Apartment buildings in Grozny, Beirut and Homs didn’t destroy themselves.

This article will look at both the vehicle and its main weapon.

The thirty-ton 2S4 mates its M240 heavy mortar to a tracked GMZ vehicle chassis used in numerous other self-propelled weapons systems. The crew of nine (four vehicle operators and five gunners) is protected by up to twenty millimeters of armor—adequate protection against small arms and shrapnel.

Though the terrifying barrel of the M240 is pointed forward when the vehicle is on the march, when deployed the mortar’s baseplate is flipped over the back of the vehicle on to the ground so that the tube points upward and away. Each shot makes the entire vehicle ring like a giant bell.

Unlike most mortars, the M240 is a breech-loaded weapon.

It can fire massive 221-pound F864 high explosive projectiles—each 1.5 meters long and comparable in weight to small aerial bombs—at targets over nine kilometers away. With rocket-assisted projectiles, the range can increase up to twenty kilometers. However, the M240’s rate of fire is just one round per minute.

Unlike a shot from a howitzer, mortar rounds plunge downward on a near-vertical trajectory, and are therefore effective for shooting over the walls of fortifications, down into cave mouths, on the far sides of mountains and piercing through the roofs of buildings.

The M240 mortar can fire a variety of special-purpose rounds for these purposes. Concrete-piercing shells are designed to shatter bunkers, while Sayda incendiary projectiles set buildings aflame. A nuclear 3B11 shell also exists. The 2S4 was deployed at high-level nuclear-artillery brigades during the Cold War.

Recently, Syrian towed M240 mortars were identified firing cluster munitions in action for the first time. A rocket-assisted 3O8 Nerpa “cargo shell” which deployed fourteen O10 parachute sub-munitions was identified as having struck a school in session in the suburbs of Damascus.

The 2S4 also can fire the 276-pound Smel’chak (Daredevil) shell, which is guided by a separate laser designator. Detailed accounts of combat in Afghanistan describe using the Smel’chak to drop shells precisely over fortress walls and into fortified cave entrances. Daredevil rounds offer a significant ability to hit point targets after just one or two ranging rounds, though the targeting system requires optimal atmospheric conditions.

The Syrian Army is currently using towed M240 mortars in its sieges of rebel-held cities. Reports on its use in the indiscriminate bombardment of Homs gained extensive media attention in 2012. (Claims that 2S4 vehicles were used appear to be inaccurate.) Previously, the mortars had also gained infamy for killing hundreds in bombardments of Beirut during the 1980s—the shells powerful enough to pierce the roofs of concrete shelters.

Egypt is also believed to retain towed M240s.

Russia maintains just one active battalion of eight 2S4s in service, with over four hundred in reserve. In 2000, Tyulpans played a prominent role in the siege of Grozny in the second Chechen war, systematically “leveling” the city from afar according to one analyst. 127 targets were reported destroyed by Daredevil laser-guided rounds. All together the Russian army claims to have killed 1,500 separatist fighters in Grozny in a siege believed to have killed over sixteen times as many civilians.

Unlike other Russian artillery systems, the 2S4 was not exported within the Warsaw Pact, with the exception of a small number of vehicles briefly serving in the Czech army.

Curiously enough, however, 2S4s were spotted in Ukraine in July 2014 by OSCE drones. It seems that in the Russian army you can take your siege mortars with you when you volunteer abroad! At least four mortars are reported being used in support of Russian separatists.

The Tulips established a reputation for themselves in the sieges of two strongpoints held by Ukrainian Army forces in 2014, the airports of Luhansk and Donetsk. In both cases, their bombardments collapsed airport terminals onto their foundations, forcing defenders to retreat from positions they had held for months. Ukrainian defense minister Valery Gelety even initially claimed in September that the 2S4 had struck Luhansk airport with a tactical nuke. He later maintained that he was referring to the vehicle’s capability of deploying nuclear shells.

My two-part article on the combat employment of the M240 mortar covers additional details on the weapon’s use, ranging from the 1973 Yom Kippur War to the present day.

The 2S4 has no equivalent in Western militaries. This is because its main task—destroying immobile, fortified strongpoints with its powerful shells—is typically performed by airstrikes using precision-guided munitions such as JDAMs. Of course, the advantages of a ground-based system are those of sustained fire over time and ability to operate when air power is unavailable.

Unfortunately, these practical characteristics have also enabled the M240 mortar’s use in prolonged and indiscriminate bombardments of civilian targets.

In the words of journalist Paul Conroy, present at the siege of Homs: “I lay there and listened as salvos of three of these mortars were launched at a time, 18 hours a day, for five days.”

Sébastien Roblin holds a Master’s Degree in Conflict Resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring.

Image: 240-millimeter self-propelled mortar 2S4 Tyulpan. Wikimedia Commons/Vitaly V. Kuzmin