The fact that they are armed is why there is a war in the first place, I think you need to think again. The 20th and 21st centuries are both chock full of examples of relatively poorly armed populations waging war, even successfully against larger powers and even superpowers. Not sure how you could even possibly come to any other conclusion.

The US military *currently* would not likely engage in wholesale slaughter of US citizens.. today.... tomorrow is always a different story. It would take armed insurrection against the internal security services before the military chain of command would start to waver though.

For who could be free when every other man's humour might domineer over him? - John Locke (2nd Treatise, sect 57)