[dbbeebs]

"I, name, do solemnly swear (or affirm) that I will faithfully execute the office of President of the United States, and I will to the best of my ability, preserve, protect, and defend the Constitution of the United States." ---

----

I (insert name), having been appointed a (insert rank) in the U.S. Navy under the conditions indicated in this document, do accept such appointment and 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.

[Amelia]

that I will support and defend the Constitution of the United States against all enemies, foreign and domestic

So how does this square with the military not being used here in the U.S.A., say, to guard the borders or to keep order?

[William Terrell]

My take is that the executive branch is most likely to be that "domestic enemy", so no need to put the phrasing in the oath of the head thereof.

The place to put it is in the oath taken by the actual people that carry the weapons.