I need more context. Are we already engaged with Russia? Because I believe the current Russian doctrine is to only use tactical nukes to “de-escalate” - that is, as a defense mechanism when overwhelmed by conventional forces. Case in point, if NATO invades Russia, Russia drops a tactical nuke to bring the west to the table. Nobody wants tactical nukes to be the new norm.
And they wouldn’t target a city, they’d target a military objective such as a ship or armor formation. Or maybe an airstrip.
I can’t imagine Russia using an ICBM to decimate Kyiv, cold-war style. That is simply unconscionable and counter to their strategic and ideological objectives.
~Max