Russia is refurbishing a Cold War era self-propelled artillery system because it proved useful in Syria. This is the 2S4, a self-propelled version of the 240mm towed mortar first seen during World War II as the M240. The 2S4 is the four ton towed M240 mounted on an armored chassis that also carries the same nine man crew used by the M240. Both mortars fired the same ammunition, like the 130kg (286 pound) high-explosive shell that contained 34 kg (75 pounds) of explosives. The 30 ton self-propelled 2S4 appeared in the late 1970s and remained in production until 1988.
The 2S4 has enough armor to be safe from machine-gun fire and most shell fragments. The 2S4 has a top speed of 62 kilometers an hour on roads (and a range of 420 kilometers with internal fuel). Since it is running on threads/tracks, like a tank, the tracks wear out every few thousand kilometers and have to be replaced. But the tracks make the 2S4 capable of moving through a shot up battlefield. This is important because the Russian 240mm mortar has, like weapons of this type, short range (about 9,700 meters). It is accurate and effective at that range, especially if firing at fortifications or in urban areas.
The 240mm mortar fires a shell that can carry a variety of payloads. The basic high-explosive version can create lethal fragments out to 150 meters. But what has kept the 240mm mortar in use is the anti-fortification shell can go through several meters of earth and concrete to destroy an underground bunker or troops firing from the basement of a multi-story building. One of the incendiary shells can set fire to most of a large structure, which is useful when firing at warehouses or factory buildings. There is a rocket assisted 240mm shell with a range of 20 kilometers by using a smaller warhead and less accuracy. This was one reason why a 240mm laser guided shell was developed a decade after the 2S4 entered service. On the downside the 240mm has a low rate-of-fire (one round a minute) despite being a breach-loading (instead of dropping the shell down the barrel.) The 2S4 crew had to use a built in crane to lift the 130 kg shells up and position them so they could be inserted into the breach loading mechanism.
The Russian 2S4s were also used during the 1980s in Afghanistan, where they provided field testing for the first laser guided artillery shell to enter service; the Daredevil. Both Russia and the United States began developing laser guided shells in the 1970s. The American 155mm Copperhead entered service in 1982 and a few years the less sophisticated, but workable, Daredevil appeared. The problem with the Daredevil was that its laser detector in the shell had a narrow field of vision, so you had to fire one or two unguided shells at a target so the forward observer with the laser could be sure his laser beam would be detected by the Daredevil guidance system. This guided shell was used successfully in Afghanistan and in the early 1990s in Chechnya. By the 1990s Russia had also developed a more effective laser guided 120mm mortar system, based on Krasnopol, their version of the American Copperhead. Krasnopol entered service at the end of the Cold War and in the 1990s improved versions were developed that were small enough for 122mm artillery shells and 120mm mortar shells. It appears that this tech is being applied to Daredevil because this 240mm guided shell is now used without the two unguided shells to check accuracy. Krasnopol is effective on the first shot and the laser designator has a range of five kilometers, meaning the longer range 240mm shell could be used.
About a dozen 2S4s remained in service with the Russian Army after the Soviet Union dissolved in 1991. Another 24 were exported to Syria where they were used during the 1980s (in the Lebanese civil war) while Russia put about 400 into “safe” storage (not just left unattended in the open). These are being brought out of storage, refurbished and equipped with updated communications and fire control electronics. Based on the number of 2S4 battalions Russia recently announced were being formed up to a hundred of the 2S4s are being updated. Russia may have already done that to some of the surviving Syrian Army 2S4s.
Syria and several other East European nations obtained M240s during the Cold War. Some of those Cold War era exports are and still used. Syria used the M240 unsuccessfully against Israeli fortifications during the 1973 war and again in 1989 against anti-Syrian factions in the Lebanese Civil War. In 2011 Syria again brought out its M240s and 2S4s in 2011 for the civil war but use has been limited, until 2016, by ammunition shortages. Russia troops entered Syria in mid-2015 and with that came a lot of technical help, spare parts and ammunition to revive Syrian tanks, aircraft and artillery. The Syrian M240s and 2S4s were noted in urban fighting during 2016 and 2017, especially in Aleppo, where 2S4 shells were often mistaken for GPS or laser guided bombs.