The right and duty of the individual to refuse an unconstitutional order is a uniquely American concept. Note that the officers of the Tird Reich did not have that as part of their oaths. It is the duty of an individual to refuse to obey an unlawful order. It is not the duty of the servicemember to decide if an order is Constitutional or not. Therefore orders are assumed lawful unless they require one to perform a clearly illegal act, such as the commission of a crime.
I don't agree. I have taken the Oath of Office, and it is my duty and the duty of every other American who has taken the same oath and whose word has value to refuse any unlawful order. That includes but is not limited to refusing any and all unconstitutional orders. Part of that duty includes recognizing that (1) you lose, big time, if you are wrong, and (2) you lose, big time, even if you are right if (as is the case today) the thug in our White House doesn't recognize and respect the Constitution. Even with that penalty, it is our duty to preserve, protect, and defend the Constitution of the United States against all enemies, foreign and domestic.
Note: I am no longer on active duty. Despite that detail, my oath did not have an expiration date. I still have a moral obligation to preserve, protect, and defend the Constitution, especially as it faces the biggest domestic threat in our country's history - actually the biggest threat of any kind, ever.