Thread by @FRHoffmann1

In recent days, we have seen renewed calls for the US to supply Ukraine with ATACMS🚀, following the Kherson counteroffensive & Iran’s potential decision to provide Russia with SRBMs. ATACMS’ capability profile remains misunderstood, however. A 🧵 1/13

https://twitter.com/Tendar/status/1591091156410331137

If the United States clears ATACMS for delivery, Ukraine will likely receive the MGM-140 ATACMS Block 1A variant. ATACMS Block 1A has a range of 300 km, comes armed with different warhead types, and an unclassified CEP of 10-50 meters. 2/13

ATACMS Block IA is armed either with a submunitions or unitary warhead. The submunitions warhead variant includes 300 M74 submunitions dispersed over the target area. Each M74 ball is made of a tungsten fragmenting wall with a steel casing and incendiary pellet. 3/13

The Block IA unitary variant is armed either with a 213 kg blast-fragmentation (same as the one in the AGM-84A Harpoon variant) or a 247 kg blast-penetration warhead (same as the one in the AGM-84K SLAM-ER Harpoon variant). 4/13

These technical specifications are important. ATACMS is not just a larger and more powerful M31 GMLRS, but provides a different capability profile. While ATACMS provides more punch relatively speaking, ATACMS is an area effect and not a high-precision weapon. 5/13

In other words, ATACMS is not construed to achieve pinpoint accuracy like modern cruise missiles, for example (e.g. JASSM-ER, Storm Shadow, etc.). This is because it lacks terminal guidance and relies solely on GPS-enhanced inertial guidance during the flight’s early stages. 6/13

The relative lack in accuracy is compensated by the missile’s area effect warhead. However, this comes at the expense of hard-target kill-capability (especially for the M74 submunitions variant but also for the unitary warhead). 7/13

Hard-target kill-capability is further reduced by the relatively small warhead size. Most modern land-attack cruise missiles carry a payload of 400-500 kg, often in the form of specialized penetrator warheads. Compare this to ATACMS meagre 213-247 kg blast effect warhead. 8/13

What does this mean? ATACMS is great to engage softer targets, including airfields, missile launchers, and air defense batteries. Given the still high accuracy of ATACMS & the low overpressure required to destroy these targets (2-5 psi), one shot should result in one kill. 9/13

At the same time, ATACMS is not suitable to engage small and/or hardened targets, such as bunkers, underground facilities, or bridges. For example, the single shot hit probability of ATACMS for a 10mx10m square is only 15.9% (not including systemic error). 10/13

In other words, to guarantee a hit on a 10mx10m square (p > 98%), such as a Kerch railway bridge section, Ukraine would have to launch no less than 23(!) ATACMS. Even if the classified CEP is lower than 10 m, the number of ATACMS required would still be substantial. 11/13

Note also that a single hit would not guarantee a kill. Bridges are sturdy structures & can withstand hits from 2,000 lb bombs. A single ATACMS hit on the Kerch Bridge is unlikely to cause fatal damage, making claims like these sound ridiculous. 12/13

https://twitter.com/ChuckPfarrer/status/1581723505187778561

Overall, ATACMS would substantially facilitate the AFU’s tasks in the coming months. At the same time, ATACMS is no 21st century Wunderwaffe. In particular, it lacks pinpoint accuracy and hard-target kill-capability, which restricts its utility in some regards. 13/13