Then he lets the president know he's not going to follow the order and takes whatever fallout comes his way as the result. Either he resigns, gets kicked out of office in disgrace or the other generals rally around him and let the president know they're going to defy him. They force a Constitutional showdown over the authority of the Commander in Chief and it gets resolved in the SC. THAT'S how you handle a situation like that, NOT by going to the country you're afraid we're about to start a shooting war with to warn them the bombers are inbound.He’s the joint chief. There isn’t anymore chain of command.
That's not a credible argument that there WAS such a command.If there was no command to attack China then there was nothing to subvert.