Following illegal orders isn't a 4 star issue alone but i disgress. You need to prove this is an illegal order to begin with. That is very much in the air depending on who your favorite politician is. He has a boatload of DoD lawyers available to provide opinion and while not privy to the procedural process I would have to think legally vetting a course of action is standard faire. Anything that's gray is going to fall in the Presidents favor.
I'm sure you see this as illegal, and that's fine. I think we've drug this particular tentacle of the larger argument out as far as it can go.