We are so far outside of the Constitution that a coup would be a perfectly legitimate response.
The Oath swears to protect and defend against enemies foreign AND DOMESTIC.
No, it isn't. We may be outside the Constitution of the Framers, but we ate within the bounds of the Living Constitution. Please be aware that the federal entity observes the Living Constitution to the letter.
The Living Constitution is the Constitution whose meaning changes even though the actual words never change. It is what happened to the Constitution of the Framers after 200+ years of case law, some of it good, but much of it bad.
The late Robert Bork referred to the Constitution of the Framers as the Constitution in Exile, which is a good description.
The Oath swears to protect and defend against enemies foreign AND DOMESTIC.
And who under the law is authorized to make that determination? The generals and admirals? Their duty is to follow the Commander in Chief, and at least half the military will do so. If you are looking for a Seven Days in May scenario, it would lead to a civil war within the military that would explode into the general population. I honestly don't think that is part of the Plan.