@henra
yea your sort of right about the example, but its hard to get an exact good one.
A direct military confrontation (which you seem to suggest in this instance) by one side
Not at all, what I'm saying is, we need to send the message that we are prepared to go all out. I'm of the opinion he doesn't anymore than we do. Unlike the WW2 the results are too catastrophic.
What I'm also saying is, we can go in to Ukraine legally with Ukraine's permission and engage a relatively weak force, without officially confronting the Russians.
He has left that door open by denying any involvement. No I don't think getting involved in WW2 earlier would have saved us there, there where too many variables involved to see how that would have turned out. Hitler was intent on takng over a significant amount of the world, and that wasn't going to change.
As such the cost benefit ratio of us confronting him wasn't going to change. In this case Putin isn't going to take over Europe, he knows that isn't going to be allowed to happen and the consequences of such would be to great. He has smaller strategic ambitions, as such confronting him on a large scale will alter the calculus of what he's doing. But you need to give him a way out at the same time.
This whole sanctions thing is cr@p, there's to much at stake for that sort of thing to work in this game. Our people know it, and are only going though the motions to make it look like where doing something.