The language is US v Calley is both stark and clear:
"the obedience of a soldier is not the obedience of an automaton. A soldier is a reasoning agent, obliged to respond, not as a machine, but as a person. The law takes these factors into account in assessing criminal responsibility for acts done in compliance with illegal orders.
The acts of a subordinate done in compliance with an unlawful order given him by his superior are excused and impose no criminal liability upon him unless the superior’s order is one which a man of ordinary sense and understanding would, under the circumstances, know to be unlawful, or if the order in question is actually known to the accused to be unlawful."
However, in this administration and political climate? With this SecDef and President? Who have pushed out generals and admirals for questioning the legality of orders or asking clarifying questions?
I'd say that anyone who refuses any order, even a clearly illegal one, better hope their JAG lawyer is very good and happens to have friends who are high up in the chain of command. Or happens to hold a lot of crypto.