"Don't worry. I am sure they will stop after we give them the sudetenland. "

Here is the secret, Russia has already started WW3, the west is just not acting that way.

If it's almost certainly coming anyway then you may as well throw them a bone first

And if it isn't coming anyway, then you've done a little bit to screw up the plans of impending worldwide fascist domination

I'd call that a win-win