In terms of protecting supply lines, there's no way the Department of Defense doesn't have a million different strategies on which train lines, oil fields, airports, farms, etc should be prioritized to protect in case something like this happens. If it got bad enough, we would just Tiennamen Square the rebels blocking passage. The citizens might make their own bombs, but nothing home made is beating an Abrams, and the US has 10,000 Abrams tanks alone. Then there's drones, warships, jets, ballistic missiles, artillery... all against citizens who don't actually know how to fight in a war. This wouldn't be like Vietnam. The US would be fighting for it's existence, and the troops would have no infrastructure problems getting to where they needed to be.

This is why the left will never win a war. They're so militarily ignorant that it's almost laughable.