defense that every post-world war ii secretary of defense has tried to implement. and that's astounding. there have been 26 of them. this is the first time a secretary defense has ever said to the world that we have a president who doesn't understand allies. >> the former editor of "the new york times" said he believes mattis' letter as he's leaving is going to go down in the history books. do you agree? >> it's one of the great state documents of the united states and it's a challenge to national security, members of congress. republicans or democrats. they have a chance starting in january to use subpoena power, to ask questions of the trump national security team. what is your strategy? where are you going? okay, pull out of syria. what happens when iran takes control? okay, pull out of afghanistan, what happens when the taliban starts to assist islamists again? there have to be these questions. there has to be a use of subpoenas. there has to be a willingness to step up and say even though congress is not number one in