"I do solemnly swear(or affirm) that I ill support and defend the Constitution of the United Sta tes against all enemies foreign and DOMESTIC!.
Well the ones taking the oath and breaking it are the DOMESTIC enemies. They have to protect the Constitution against the likes of themselves. See how silly that is?
Now the oath orginater never imagined the oath taker would be an enemy. That was something unforeseen. too bad.