Seems like a waste of a ICBM.
Or just using up old inventory.
If it was an RS-26, here’s what ChatGPT has to say about that one:
The RS-26 Rubezh is a relatively modern Russian intercontinental ballistic missile (ICBM), so it would not be considered “old inventory.” It is designed as a part of Russia’s strategic nuclear deterrent and is seen as a successor or complement to older systems like the RS-24 Yars. The RS-26 Rubezh, which is based on the Yars platform, was first publicly unveiled in 2014 and is a solid-fuel missile intended to be more mobile and potentially more difficult to intercept than its predecessors.
The missile has been described as having a range of up to 4,000 kilometers, though its precise capabilities and deployment status are somewhat shrouded in secrecy, and much of the public information about it has been limited. It’s not widely deployed or in large numbers, so it might be considered a newer asset within Russia’s strategic forces rather than part of any “old inventory.”
In general, Russia has been modernizing its nuclear forces, and the RS-26 fits into that strategy, alongside other new systems like the Sarmat ICBM and new submarine-launched ballistic missiles. Therefore, while not the newest system in Russia’s arsenal, the RS-26 is still part of an active and modern inventory rather than being considered outdated or old stock.