It has been amusing to watch many assume that the "S-400" missiles reportedly being launched in a surface-to-surface mode against Ukraine are standard SARH 48N6 surface-to-air interceptors. Ukrainian intelligence has been talking about Russia adapting the underlying design as a purpose-built surface-to-surface missile with the designation RM-48U for some time. All things considered, and the significant limitations of the RM-48U notwithstanding, this is a rather smart move on the part of Russia. I wouldn't be surprised if (actual) 48N6 stocks and production exceed requirements, at least in the near term, while 9M723 Iskander-M production remains inadequate for wartime needs. The RM-48U is hardly optimal for the role and has limited range for Russia's purposes in the Russia-Ukraine War, but nevertheless facilitates larger and more regular "ballistic missile" salvos, which can further draw upon Ukraine's finite stocks of BMD interceptors. Furthermore, there exists a very large pool of (ordinarily) SAM launchers that can launch up to four of these at a time, which is no small thing once you consider how, as per Ukrainian intelligence, Russia currently lacks enough 9M723 Iskander-M ballistic missiles for all 100+ associated launchers, let alone all the reloading vehicles assigned to said launchers. The S-300 and S-400 have always had a surface-to-surface mode and the practice of employing SAMs in this manner is hardly new. Russia has been doing so since 2022 as a result of critical munitions shortages (as I recall, this initially/previously concerned the use of older 5V55 interceptors employed by S-300 batteries, which are being gradually phased out—some of the 5V55 interceptors are very old). Consider also the South Korean (Ameircan-built) Nike Hercules turned Hyunmoo-1 ballistic missile. I remember @fab_hinz wrote his masters thesis on the surface-to-surface mode for the S-300, which anyone interested in the technical particulars may find informative. Finally, I am curious to know which part of the Russian military operates these S-400 launchers with RM-48U missiles. The S-400 is VKS system, not an SV system (the PVO-SV operates the essentially unrelated S-300V), while the 9M723-M is an SV system. Is the VKS now in the ground-launched strike capabilities business? The VMF now appears to be with the ground-launched 3M22 Zircon (reportedly using modified Bastion-P launchers). There is also the peculiar and under appreciated dynamic concerning how the conventionally armed Oreshnik is operated by the RVSN RF (which otherwise only operates nuclear-armed missiles), not the SV, which operates the 9M723 Iskander-M. I have also seen at least one Ukrainian source recently talking about VKS-operated Gerans, although I am unsure if this accurate (ordinarily operated by SV units, the Geran-2 is also employed by the new VBS). 1/