"It's time to deal. I've locked in my forces in to exactly where I want them to be. Allow me a gracious way to get out of this. You remember Serbia, don't you? When it was clear I couldn't have Serbia, I destroyed it! Do you want that to happen to your precious Ukraine?? You have been warned!"
Think about the Ukranian people, cut the deal and get this over with. (JMHO)