You have no idea how interconnected the world is, do you? How reliant the US is on its ports. Not just any place on a coastline is big enough to pull a cargo ship up to, as well as having the infrastructure to unload it and coordinate all that. All they have to do is hose every port capable of handling cargo ships and we are entirely fucked. The cherry on top would be nuking the oil refineries, completely wiping out our ability to move goods even if the ports were open. We will not have enough food to feed the country within a few days. Mass starvation starts a week or so afterwards. Two to three weeks later and at least a quarter or more of Americans will be dead from starvation. Then comes the massive waves of diseases due to all the unburied dead. Inside of two months at least half of America will be dead or dying. More likely to be closer to three-quarters.

All out nuclear is not something we survive.