Thread by @BrynnTannehill

It's starting to actually look like Ukraine will get ATACMS (aka MGM-140). A short discussion is probably in order about how this came about, how it will be implemented, and what it's operational implications are. 1/n abcnews.go.com/Politics/us-se…

The basics (for people who don't already know) is that ATACMS is a GPS and Inertially guided Short Range Ballistic Missile (SRBM) that can be fired from HIMARS or the M270. It weighs about 2-tons, and has ~500 lb war head w/a range of ~190 nm (300 km). 2/n

Up until now, the US has steadfastly refused to supply ATACMS. The suspected reasons range from worries that it would cause Russia to escalate, fears that Ukraine would use US made weapons on Russian soil, and that the US needed them for other theaters. 3/n

Only ~3700 have been built, and many of those have either been used in conflicts or sold to other countries. It is unknown publicly how many the US has in inventory now, or how deep the US believes it needs its ATACMS magazine needs to be. 4/n

ATACMS is an older weapons system: it was introduced in 1991, and it is planned to replace it with the longer ranged Precision Strike Missile (PrSM), whose Initial Operational Capability (IOC) is expected in CY23. PrSM can be fired from HIMARS. 5/n news.lockheedmartin.com/2022-09-27-loc…

Likely as a result of observing the war in Ukraine, the US has ordered more ATACMS in the FY23 budget, and bought more Early Operational Capability PrSMs. But, some reports say that the US "found" additional missiles. There's a likely explanation. 6/n

Being an older system, there are probably some ATACMS that aged out (most likely based on the age of the solid rocket motors), and were marked for disposal. They don't register on active inventory, and the US has a lot of ancient stuff in deep storage. 7/n

I'd love to say that the system is great at tracking everything, but yeah, no. I'm wouldn't be surprised in the slightest if it turned out that no one had thought to on-site check expired munitions awaiting disposal, but later found ATACMS that weren't on active inventory. 8/n

What does expired mean? Well, basically it's how long can something sit in storage and still have an acceptable "dud" rate. Solid rocket motors on missiles is one of the big items: they can develop cracks. You don't want them exploding or misfiring in the tube or on the rail. 9/n

The upshot of this is that at a minimum, these ATACMS are going to need to go through an inspection before they go out, particularly of their rocket motors. Catastrophic failure could destroy the HIMARS launch vehicle. 10/n Video is RU SAM misfire.

This means a delay. There's also going to be the matter the HIMARS systems in Ukraine: ATACMS capability was removed before they were sent. There's also probably going to be insistence on mods to ensure they can't be used on RU. 11/n thedrive.com/the-war-zone/u…

So, more delay. I cannot tell you how long the delay will be, but I'd advise a certain amount of patience if things don't seem to be happening quickly enough: you REALLY don't want these things misfiring, exploding, or not going where they're supposed to. 12/n

Some other reasons for the potential change of heart is that SCALP-ER and Storm Shadow already provide a deep-ish strike capability. The US may also want to prod Germany to start supplying Taurus Cruise missiles (which are on a par w/ SCALP). We've seen this before w/ tanks. 13/n

So what does this mean tactically, operationally, and strategically? First off, SRBMs are harder to shoot down than cruise missiles. The only Russian SAM system with a credible Anti-Ballistic Missile (ABM)capability is the S-400. 14/n missilethreat.csis.org/defsys/s-400-t…

Patriot has performed well against SRBMs (Khinzal / Iskander), but Russian equipment has a nasty habit of over-promising and under-delivering. And ABM intercepts are HARD. The US struggled mightily for decades to get it even sort of right. 15/n

Top initial target is likely to be S-400 radars first (to remove the only Russian capability of shooting down ATACMS). ATACMS flies quickly enough that the S-400 sites probably can't pack up and leave quickly enough. I'd expect coordination with Storm Shadow launches. 16/n

After that, focus will be on exceptionally high value targets too far away or too well defended to hit with scarce cruise missiles: hardened C2 nodes, ships that are pier- side in Crimea, large ammunition depots, Kerch (and other) bridges, high value aircraft. 17/n

Which brings up the question: what will the effect be? It's not a wunderwaffe: it will not single handedly win the war. But oh wow, will it complicate things for the Russians. ATACMS can hit everywhere in occupied Ukraine (including Crimea) with minimal warning. 18/n

ATACMS give Ukraine the ability to hold most Russian high-value assets at risk as long as they are in Ukraine. This creates all sorts of dilemmas and calculations with no good answers. 19/n

One of the first is trying to assess if something is valuable enough for Ukraine to spend a precious, limited resource ATACMS on it. Would Ukraine use one on a Colonel? A brigadier general? One or two Ka-52s? A barracks in Mariupol? A small corvette in Sevastopol? 20/n

How big does the ammunition dump have to be before Ukraine decides it's schwackable? It's unknowable, and allows Ukraine to potentially exercise reflexive control. Ukraine might not think that a corvette or colonel is really worth an ATACMS. But let's war-game it out. 21/n

If Ukraine hits a target that's not worth it, but it gets a desired behavior, it can be worth it. For example, blowing a 20 foot hole in a ship from the deck through the keel might induce Russia to pull ships out of Crimean ports. 22/n

Outside of port they're more vulnerable to drones. So, Russia pulls their warships further back. This is a win. So is it if you induced most senior Russian officers, to all hide far from the front in a bunker back in Rostov. Or pull all their Ka-52s back to Russian territory 23/n

Sure, the Ka-52s can fly to the front from inside of Russian territory, but their loiter time is greatly reduced, because it adds an additional 50 nm distance they have to fly to get to the front if they're operating out of Taganrog. 24/n

Much has already been written on ATACMS and Kerch, but suffice it to say ATACMS could have significant effect on GLOC choke points.

The biggest gain is ATACM's ability to shape Russian behavior, which has bigger downstream tactical, operational, and strategic effects. 25/n