Russia would give us a run for our money. And if other mutual enemies decided now if the time to punch the bully in the mouth, China, Iran, NK could make it very interesting. Im sure we can bend the arms of our "allies" to join the fight but really none of them really like us much either. And if (And i am being hypothetical here, i really dont think anyone is stupid enough to do this) this were to actually go down there would have to be a draft. Which means your kids will have to go and fight over a lie and over something that had absolutely nothing to do with us. Like WW1, WW2 europe, Vietnam, Kosovo, Desert storm, Afghanistan, Iraq, Libya, blah blah. Does anyone really buy this shit?