Another blog post from William “Chip” Sayers:
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Week before last, Russia launched what was probably a small number of RS-26 Rubezh Intermediate Range Ballistic Missiles (IRBM) at the city of Dnipro in Ukraine.[1] There are a number of interesting points to this incident, as well as a number of misconceptions. Let’s try to make sense of this strike.
First, a lot of cages have been rattled over the fact that this is the first time an IRBM has been fired in anger. The reason why this is a cage-rattling event is that IRBMs in general are a nuclear weapons delivery system, and the launch of an IRBM could, in theory, trigger a nuclear response by an interested party on the other side. This goes to the Cold War doctrine of “launch on warning” — in other words, to launch one’s own nuclear missiles when the enemy’s incoming missiles are detected on radar (“warning”), but before they have struck their targets.
Under this scenario, Russia might launch a small number of IRBMs at Ukraine, and when US sensors detected this, the American President would mistakenly interpret this as a nuclear attack on the United States and launch the US nuclear arsenal at Russia. At this point, the Russians would then launch their nuclear missiles and we all go to hell in a little rowboat. I’m not certain as to why this might happen, particularly — as in this case — if the IRBMs are armed with something other than nuclear warheads.
Frankly, Putin was apparently fairly confident that such a limited strike would not trigger global thermonuclear war and, in this case, we crossed that threshold with no discernable harm. Unfortunately, it was a real threshold and Putin now has the leeway to use this new class of weapon with impunity. So, let’s unpack some facts about the weapon Putin used to fire this particular shot across the West’s bow.
The first thing to understand is that the SS-26 Rubezh — or “Oreshnik,” as Putin called it — is not an operational missile. Development of the system began in 2008, based on a two-stage version of the RS-24 Yars ICBM, with the first test launch in 2011.[2] The missile’s first successful test flew 5,800km, which technically qualified it to be called an Intercontinental Ballistic Missile (ICBM), i.e., a missile designed to strike the United States. However, all subsequent test flights have been to much shorter range, betraying its true purpose as an IRBM designed to attack European cities and therefore making it a violation of the Intermediate-range Nuclear Forces (INF) treaty. It is not surprising that the missile that triggered the effort that culminated in the INF treaty — the SS-20 — was, itself, a cut-down version of a 1970s-era ICBM. [3] Interestingly, all four missiles are from the same design bureau, so everything old really is new again.
It was the SS-26, along with other blatant violations, that caused President Donald Trump to withdraw the United States from the INF treaty in 2019.[4] Ironically, Russia suspended the SS-26 program, apparently due to the lack of adequate funding.[5] We can’t be entirely sure that Russian Rocket Forces general who announced the suspension was telling the truth, as opposed to misleading the West with disinformation. Nevertheless, it seems plausible that the RS-26 program was suspended, and that a small number of the test missiles have been in storage awaiting more funding to complete testing.
It is further plausible that, in anticipation of the US and NATO allies removing restrictions on Ukrainian use of Western weapons, Putin wanted an escalatory response to chill NATO and prevent further attacks on Russian soil. The unprecedented RS-26 shot fills that roll exactly. It remains to be seen as to how successful that signal will turn out to be.
So, what exactly did we see last week? Video images appear to show six distinct events with 4-6 ground impacts with each event. Of note, the reentry vehicles (RVs) or submunitions, as they’ve been described, did not appear to be explosive. We will discuss that in more detail, in a moment. The RS-26 has been commonly described as having four Multiple Independently Targeted Reentry Vehicles, or MIRVs.[6] Some analysts believed Putin’s statement that this was a single missile traveling at Mach 10 with six MIRVs, each with four to six submunitions. One went so far as to make a rough estimate that one of these submunitions, weighing 100kg, would deliver the equivalent energy of a Mk 84 2,000lb bomb through kinetic energy, alone.[7] Is this possible? Yes. Is it likely, No.
As we learn more about this attack, we may find that it was, indeed, a single missile. However, my immediate reaction was that this was six missiles with four Multiple Reentry Vehicles (MRVs), each. As the name somewhat obliquely implies, MRVs and not independently targetable, but rather are fired as a barrage at a single area target. Certainly, if they were MIRVs, their independent targeting capability was wasted. More to the point, ballistic missiles are all about throw-weight, and a MIRV Post-Boost Vehicle (PBV), or “bus” — the final maneuvering stage that drops off MIRVs on trajectories toward different targets — is a heavy and complicated piece of machinery.[8] Having a MIRV bus on a missile that was loaded with MRVs is a huge waste of throw-weight: it would be better to download the bus and use the extra weight allowance for more, or larger MRVs. According to CSIS, the RS-26 has a total warhead lift capability of 800kg.[9] If CSIS’s estimate is accurate, the missile could never lift 3,600kg of MIRVs — unlikely even with the bus offloaded.
Particularly unlikely seems to be the idea that these were MIRVs with submunitions. What would be the point? This would only add complexity and unnecessary weight to the missile. No missile has ever been tested with multiple reentry vehicles that split open to release submunitions. A reentry vehicle designed to split open seems like a summons to disaster — a seam between parts of the aeroshell sounds like an invitation for hot plasma to enter the RV during reentry. More to the point, what purpose could submunitions possibly serve? Why not make each submunition an RV of its own and forego the extra complexity of packaging them into a larger MRV?
Putin claimed that there is no way to defend against the RS-26. He referenced the missile’s Mach 10 hypersonic speed and implied that it had Maneuvering Reentry Vehicles (MaRV) to evade defenses. Generally speaking, the longer-ranging the ballistic missile, the higher the speed of the RVs. Yes, travelling on the end of an IRBM, the RVs will come downhill at Mach 10, or better. No, what we saw in the video did not reflect MaRVs — and it is highly unlikely that all of the elements that have been claimed for the missile (MaRVs with submunitions, etc.) could be combined.
Hypersonic speeds are nothing new, nor particularly remarkable. The Soviet’s SS-1c SCUD SRBM dating back to the late 1950s reached hypersonic speeds, but even Patriot SAMs were able to shoot them down. Hypersonic missiles with MaRVs can be a problem for missile defenses, though maneuvering decreases accuracy and bleeds off speed, so there are limits to what they can do. Mach 10 non-maneuvering warheads are certainly not easy targets, but most experts acknowledge that the US Army’s Terminal High Altitude Area Defense (THAAD) missiles are technically capable, the Navy’s SM-3 are capable, and the Army’s Ground-Based Midcourse Defense missile are certainly capable of shooting down the RS-26. So, Putin’s boast that there is no defense against the RS-26 rings hollow.
In sum, the use of the RS-26 in Ukraine marks a provocative, though not revolutionary event. Putin risked much in using an IRBM in combat for the first time, but the weapon did not visibly achieve much on the ground, and probably cannot easily be reproduced, given its likely status as a developmental program that has been suspended. This was almost a move of desperation to signal Putin’s unpredictability and willingness to use measures that test the limits of rationality. We shouldn’t be impressed.
[1] What is RS-26 Rubezh intercontinental ballistic missile or ICBM, range and can Russians really launch it?, Indiatvnews.com, 21Nov24, https://www.indiatvnews.com/news/world/what-is-rs-26-rubezh-intercontinental-ballistic-missile-or-icbm-range-and-can-russians-really-launch-it-dnipro-2024-11-21-962729. Accessed 23Nov24.
[2] Stefan Forss, “Russia’s New Intermediate Range Missiles – Back to the 1970s,” Atlantic Council, April 6, 2017
http://www.atlanticcouncil.org/blogs/natosource/russia-s-new-intermediate-range-missiles-back-to-the-1970s. Accessed 24Nov24.
[3] https://russianforces.org/blog/2013/12/more_news_about_rs-26_missile.shtml. Accessed 24Nov24.
[4] https://www.washingtontimes.com/news/2013/jun/25/russia-violating-1987-nuclear-missile-treaty/ Accessed 25Nov24;
[5] https://russianforces.org/blog/2018/04/by_cancelling_rs-26_russia_kee.shtml Accessed 24Nov24; https://www.theguardian.com/world/2018/oct/20/trump-us-nuclear-arms-treaty-russia Accessed 25Nov24.
[6] RS-26 Rubezh, Wikipedia, Accessed 26Nov24.
[7] “Now I’m Really Scared: The New Oreshnik Missile Attack on Dnipro,” Millenium7* History Tech, https://www.youtube.com/watch?v=iL7Hb0fcpbU. Accessed 25Nov24.
[8] Defense Intelligence Ballistic Missile Analysis Committee, Ballistic And Cruise Missile Threat 2017, 9.
[9] Missiles of the world — Russia — “RS-26 Rubezh,” Missile Threat – CSIS Missile Defense Project, https://missilethreat.csis.org/missile/ss-x-31-rs-26-rubezh/ Accessed. 27Nov24.
