USA + Europe will win a crushing nuke war against East.
Russia will be defeated, but they're tough. Europe will be battered, again. Middle East devastated and Israel destroyed.
But we gotta handle China. They're all business. And the Saudis. We owe China. We're addicted to oil. They wouldn't mind cutting us off.
But in the devastating end U.S.A would win WWIII.
No one wins in a nuclear war, the US won't be able to successfully invade and occupy a nation like China, Russia, India etc. In a world war, the US wouldn't win a decisive victory, even with allies. I'm not saying that the US would lose, I'm saying it would be a long war of attrition, with a long stalemate.