"I, _____, do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; and that I will obey the orders of the President of the United States and the orders of the officers appointed over me, according to regulations and the Uniform Code of Military Justice. So help me God.
All enemies, foreign and domestic. That takes precedent over the orders of the President and officers in the enlisted mans oath above and is the central focus of the officers oath below. Preserving and defending the constitution is the primary duty of all our service men and women.
I, [name], do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter. So help me God.
Some people seem to think that a majority our troops will blindly follow unconstitutional orders and act against the people, I don't think they will. If they do, its the very definition of tyranny and a constitutional crises. As long as we continue to follow the constitutional process all should be well though.
For those who say times dictate change, Article V of the Constitution spells out the processes by which amendments can be proposed and ratified. Its all clear as day. Its simple really, follow the constitution and the rule of law and all will be well. Try and institute radical, unconstitutional change and all will not be well.
In my estimation it would take about 1/3 of the population and a significant portion of the military to launch a full scale revolution. Now who really sees that happening in the foreseeable future? I know I don't, but...history has taught us that tyrannical governments can spring up unexpectedly. None of us know what the world will look like five years from now, more less twenty. So we really can't say what might transpire.
PS: If someone is out there thinking our current government needs violent revolution wrought against it, you need your head examined.