The oil is in red states, as are the primary refineries. Imports easy to interdict. So food can’t move to city shelves and the war would end in 1 week with very few deaths.
Blue states and cities will be perfectly happy to get their oil from traditional America’s enemies like Venezuela, Iran gand even Saudi Arabia and other gulf countries.
Deep blue states will happily get all the food from overseas as well. Anything destroy the “Great Satan” or the “capitalist pigs”
What countries will come to red states aid?
Britain?
France?
Germany?
Japan?
Etc.
Etc