From what I can see, H.R. McMaster may be Trump's best appointment by far. If you've been following the news, you know about his acclaimed Ph.D. dissertation: "Dereliction of Duty: Lyndon Johnson, Robert McNamara the Joint Chiefs of Staff, and the Lies That Led to Vietnam." Here are some of takeaways from the dissertation:
The president was lying, and he expected the Chiefs to lie as well or, at least, to withhold the whole truth. Although the president should not have placed the Chiefs in that position, the flag officers should not have tolerated it when they had.
There was no meaningful structure through which the chiefs could voice their views — even the chairman [of the Joint Chiefs] was not a reliable conduit. NSC meetings were strictly pro forma affairs in which the president endeavored to build consensus for decisions already made.
The disaster in Vietnam was not the result of impersonal forces but a uniquely human failure, the responsibility for which was shared by President Johnson and his principal military and civilian advisers. The failings were many and reinforcing: arrogance, weakness, lying in pursuit of self-interest, and above all, the abdication of responsibility to the American people.