Trump and his threats to Canada. First, let's look at NATO countries and then Article 5.

[usaf-vet]

2. The protection for military members who refuse to obey an unlawful order is found under Article 92 of the UCMJ.

Article 92 of the Uniform Code of Military Justice (UCMJ) protects military members who refuse to obey an unlawful order.

UCMJ Article 92 – Failure to Obey an Order or Regulation
Article 92 requires service members to obey lawful orders.
It explicitly does not require obedience to unlawful orders.
Refusal to follow an unlawful order is not a violation of Article 92.

Legal Foundation
U.S. military law recognizes that “I was just following orders” is not a defense for committing an illegal act.
This principle was established clearly after World War II, particularly during the Nuremberg Trials.
The U.S. Department of Defense Law of War Manual reinforces that military personnel have a duty to disobey manifestly unlawful orders.

Examples of Unlawful Orders
Orders to kill civilians
Orders to torture prisoners
Orders that violate the Constitution or international law

Bottom Line
A military member is legally protected when refusing to obey an unlawful order. The burden is on the individual to recognize that the order is clearly illegal—this is not a get-out-of-jail-free card for disobedience, but a serious responsibility.