You'd be right if he used nukes.  But I think a limited well-signaled conventional military strike under Article 51 would unify many corners of the world WITH Russia not against.

Most countries in the world secretly resent the USA but play along with them because they know who has the power.  Once BRICS showed up and Russia-China relations warmed, we started to see many nations that seemed like Western allies turn away from strict allegence to the West, either to hedge their bets and play both sides, or to join the other side economically, or policy wise, or sometimes even militarily.

Negotiation is the best path if all sides want it.  Maybe some European countries want to negotiate.  Does the UK?  Does the US?  Does Ukraine?  Are they signalling this by launching ATACMS and Storm Shadows deeper into Russia?