accomplishing or preventing it wasn't happening anymore. mr. trump essentially has become not only his own national security adviser, he has also become his own secretaries of defense. >> you saw that reserve that mattis had, if you remember that early meeting of the cabinet where trump forced cabinet officials to go around almost in a north korea fashion pledging fealty and loyalty to him and mattis was the one who refused. he said it's an honor to serve the american people and lead the armed services. he made no reference to trump. again, in this letter of resignation to me the most interesting part is the omission. he doesn't thank trump personally. >> no, again, he ended it with a reference to the men and women in uniform. he was in that sense true to himself. there were so many signals in this letter. this is one of those great things that historians will look over. what i liked about it, it's so rare in washington where people actually resign and then resign on matters of principle and policy and it wasn't ad hominum,