History is full of examples where soldiers have refused orders to fire on their own people. Revolutions often start that way.
America is full of recent examples of soldiers ignoring their oaths.
And you think the average soldier is trained on what their oath to the constitution should actually mean?
When I joined the Navy, I swore an oath to support and defend the Constitution. But not once, in all of my training, did I receive meaningful instruction on the document to which I had pledged my life.
Should that point arrive, those charged with carrying out such orders will bear an enormous burden. From my time in the Navy, and from conversations with those still in uniform, I fear that the American military is not prepared. It has failed, at every turn, to provide those charged with defending the Constitution even the most basic understanding of what it means.
https://www.theatlantic.com/ideas/archive/2020/02/us-military-not-ready-constitutional-crisis/606367/