EMP is possibly a more significant concern. It would be... hard to estimate how the world would respond to an EMP - we would suffer devastating damage, but nobody wants to be the one to start an outright nuclear war either. It would likely lead to declarations of war at the least and conventional attacks which is why Putin is still, 95% most likely, not ever going to employ it.

Outright Nukes though? Little question that Russia would "get fucked" and Putin knows it.