There is a point where war is unavoidable, and the problem with fights between 2 parties is simple: if one party believes it is in a fight ... you're in a fight. It does not matter what the other party thinks.
If Putin believes we're at war with Russia, we are at war with Russia and we will need to fight. Fight a little or a lot? Today we could fight a little. Tomorrow we will have to fight a lot.
Our red line is NATO, same as it always was. And will Russia have greater or lesser capability to wage war in a year or two, with their economy ruined by sanctions? Dependence on international trade today is far greater than anyone could have dreamed in the 1930s, and it's dangerous to try to force historical analogies that simply don't hold up under scrutiny.