What does the average American have that can stop a tank, or an armored personnel carrier, or a jet, or a helicopter.
Iraq disbanded its military, all those guys went home with AK-47s and knew where the ammo depots were. The IEDs beating our guys are up often artillery shells wired to a cell phone. We all have cell phones, who knows how to get artillery shells in the US? Not nearly enough people to make a decent fight.
The only way it could happen here is if a significant portion of the US military sided with the revolutionaries - ironically what happened in both the American Revolution and the Civil War. There is no example of a successful revolution based solely on civilian soldiers. A lot of the people in the US army during the revolution were civilians prior to the shooting, but they were led by men who had fought in the French & Indian war for the British.
So if some of the military is joining the breakaway sect, robots or not will not change the situation since both sides will have them.
I'm still more worried about chemical, biological, or nuclear attack.