Posse Comitatus or something to that effect forbids the deployment of regular military on US soil in a police action. Coast Guard is exempt but not much use out of the water.
http://en.wikipedia.org/wiki/Posse_Comitatus_Act
Yep.
So they call it a war, instead of using Harry Truman’s description for Korea. Or a federal emergency, or or or.
I don’t think it will happen, but as I said above, interesting exercise of the brain.