I know this old but one nuke isn't gonna end the world. It'll make a whole continent uninhabitable for ten thousand years years, but it won't end the world. In WW2, the US nuked Japan with a less powerful nuke. To end the the world, Russia would have to attack the US's biggest cities and the US would have to do the same to Russia. Sorry I'm big nerd and I don't like seeing factually incorrect statements.