Ted answered the hand-wringing liberals on this. He simply deferred to what the founding fathers thought about an armed populace and government tyranny.
Also, the federal government is prohibited by law from using the military against civilians by the Posse Comitatus Act. The National Guard is your neighbors and your friends. They aren’t going to take up arms for the government. The local police want to go home at night to their families.
What they will do is send the "neighbors" of one state against the "neighbors" of a different state. And Yes, they will take up arms. This happened once before a long time ago.
At this point I usually quote the Anti-Federalist papers.
Thirdly, the absolute command of Congress over the militia may be destructive of public liberty; for under the guidance of an arbitrary government, they may be made the unwilling instruments of tyranny. The militia of Pennsylvania may be marched to New England or Virginia to quell an insurrection occasioned by the most galling oppression, and aided by the standing army, they will no doubt be successful in subduing their liberty and independency. But in so doing, although the magnanimity of their minds will be extinguished, yet the meaner passions of resentment and revenge will be increased, and these in turn will be the ready and obedient instruments of despotism to enslave the others; and that with an irritated vengeance. Thus may the militia be made the instruments of crushing the last efforts of expiring liberty, of riveting the chains of despotism on their fellow-citizens, and on one another. This power can be exercised not only without violating the Constitution, but in strict conformity with it; it is calculated for this express purpose, and will doubtless be executed accordingly.
This was written December 12, 1787. How prophetic it was.