The lines are a bit blurrier here than you might think. Soldiers are required to disobey illegal orders. Congress declares war. But the President has the right

The lines are a bit blurrier here than you might think. Soldiers are required to disobey illegal orders. Congress declares war. But the President has the right to respond militarily in an emergency - war does not wait on committees. If Trump had said that e.g. NK had attacked, and ordered that NK be nuked, but NK had not actually attacked (i.e. there was not actually an emergency), that would have been an illegal order, which soldiers would have been legally bound to disobey. It would be treason for Milley to countermand a legal order, but asking for key servicemen to review the details of an admittedly complicated bit of military law and to prepare themselves for exactly what decision they might need to make in realtime - nothing illegal about that.