It would be more than that, a launch without any pre-existing escalation is unlikely, I’m not sure what the US or Russia for that matter would do in case a “rog

It would be more than that, a launch without any pre-existing escalation is unlikely, I’m not sure what the US or Russia for that matter would do in case a “rogue” launch. We know from a few previous close calls that the Russians didn’t launch when they erroneously detected launches. Quite likely any nuclear engagement would be preceded by an adversary trying to destroy or minimize your second strike capabilities first. The US keeps its SLBM fleet in a rotation that would always be optimal for a second strike against Russia. Russia increasing its anti submarine activity or even destroying US subs would likely be seen as a prelude to a first strike. So Russia spending 3 months pushing US subs into a kill box further and further form optimal launch positions and then the US detects a ground based launch no matter how small would likely invoke a ground based launch from the US before anything actually hits.