Russia will no sooner surrender to American-backed forces in Ukraine than we would surrender to a Russian-backed insurgency in Vermont. The situation is hardly analogous—unlike Vermont, Ukraine is a country—but from Vladimir Putin’s point of view it’s precisely analogous.
This is all about NATO expansion which scares the daylights out of the Russians. It shouldn’t, but it does, and it’s not hard to understand why. Just ask yourself how the British would feel if the USSR won the Cold War and the Warsaw Pact expanded to Paris and Brussels. London would feel like it’s “next.” London would have cause to feel like it’s “next.” That’s exactly how it looked from Moscow’s point of view when former vassals like Lithuania and Estonia joined up with Germany and France—and the United States.
It’s a paranoid analysis, but Russia has always been paranoid.