Even taking the nuclear threats out of the equation and pretending the war is won easily, the question of Ukraine's eastern regions remains. If a majority of citizens of Donbas want to be part of Russia, would NATO help Ukraine wage the same war against insurgency its been waging for years? It's a very messy question. I think I'd prefer Ukraine to cut their losses and recognize Luhansk and Donetsk as independent before supporting sending planes in.