And to extend this hypothetical a little: the nuclear arsenal of people attacking the US is not as good as the one in the US. Odds are anyone dumb enough to th

And to extend this hypothetical a little: the nuclear arsenal of people attacking the US is not as good as the one in the US. Odds are anyone dumb enough to throw a nuke at the US is doing so with some really cunning plan in mind hoping for retaliation, and doing so with a nuke that's far from optimal. Russia and China are better served by eating up the US economy (and government!), than balls-to-the-wall war, so it's more likely an country that 'also has nukes' than the players with the real budgets.