back in the '90s, we (Army E-4) had talk about shooting US citizens. it was pretty clear in my unit that we would say no, with some exceptions. we would protect the Constitution and the Office of the Presidency, but not the Person. we are a Constitutional Republic, not a democracy as some people claim it. if it was a democracy, then we are only one step away of communism/socialism/authoritarianism.
if we went in as riot police in a protest, no. if the rioters were bombing or shooting at civilians, yes. Civil War, yes but you got to pick a side, either government or the rebels. in the 1860s, i along with others E-4's would go to Grey side. it was about the Rights of Self Determination, not slavery as we are taught. Lincoln in 1863, 2 years into the War, said slavery is bad, while Maryland and other Northern states that joined the Blue, still had slavery. Lincoln said something like that that he didn't care about slavery, as long as the Country remains whole. they don't care to teach you about that. or about the other policies that the US government did some 30 -40 years ago.
by the time i got out of the Army, a few years later, then 9/11 happened. i was too old (18 - 27yo can join) and my knees were and are bad, but i and some other E-4s (retired) still went to my unit and volunteered again. but we were told no, we were to old, but you can help. so we did with no pay or rank. those days i would say no to shooting US citizens.
20 years go by, and no again. but Biden stole the election, left Afghanistan to the Taliban and Biden real fuched ups, and include the Obummer's transgenderism (not his manwife, Moochelle), i say maybe no. Trump did a real pay raise, started manufacturing next gen everything, did a complete turn around on the military budget and so on. i definitely would say no to shooting US civilians.
just because a general said to shoot US civilians does NOT make it right. you say loudly, "Sir, i refuse to accept that order. i feel that i cannot shoot US civilians and i find that order illegal." he probably have you taken away, but a good lawyer (you can go to JAG or civilian lawyer) and then you go to probably a General Courts Martial (a presiding judge-lt colonel and 2 judges - 2 majors) and then give evidence and let fate decide.
https://www.historians.org/about-aha-and-membership/aha-history-and-archives/gi-roundtable-series/pamphlets/em-11-what-shall-be-done-with-the-war-criminals-(1944)/are-superior-orders-a-legitimate-defense#The%20American%20View
