Which is indistinguishable from a Russian first strike. Russia glassing Ukraine is about as rational as it launching a first strike. So serious people would have to weigh–based on incomplete information–whether Putin is still in charge and if tens of millions of lives might be saved if we neutralise their silos first.

Outside nuclear holocaust, Russia, on launching a strategic nuclear strike on Ukraine, would have crossed a red line Beijing, New Delhi and Tehran each value. (The last because Russia's justification for glassing Ukraine is easily copy-pasted by Israel.)