We also live in a world where Russia launches conventionally armed IRBMs against their neighbor.
https://en.m.wikipedia.org/wiki/Oreshnik_(missile)#First_ope...
It was not conventionally armed. It had dummy training warheads, conventional payloads for it are not even being developed. There are hardly any targets for which lobbing high explosive with an ICBM is cost effective.
This has been proven utterly false since the 1960s, because a) you can't recall an ICBM after firing it, b) you can't retarget an ICBM after firing it, and c) there's no reliable way to tell nuke warheads from conventional ones, meaning every one you launch has to be assumed to have a nuclear payload, with all the world-ending consequences that entails.
The Air Force resurrected this zombie idea (conventional ICBMs) in the 2000s and called it Prompt Global Strike, only to can it for the obvious reasons.