Should Russia "fight back"? Did NATO aligned countries cross multiple red lines with too much provocation? ... This has been argued to death, and I'm not wasting my time on that here.
Were it not for the nuclear concern, Russia could be dispatched by a modern military in short order. They're having enough of a challenge with Ukraine. Against a real military with SEAD/DEAD, you would witness an Iraq 1991-style collapse within weeks, perhaps less.
Of course, the problem is the nukes. Which is exactly why you see these countries work so hard to get them.