Cabinet members may disagree and even resign in protest, but, ultimately, they must obey the order of the Commander-in-Chief.

Richard Nixon, famously, conducted his foreign policy according to the 'madman theory': he tried to convince enemy leaders that he was irrational and volatile in an attempt to intimidate them. But this was a potentially useful approach to foreign policy only because it was an act.

It's all too easy to imagine Trump issuing an ultimate, thermonuclear 'You're fired!' to China, Iran, or another nation - and perhaps to the whole human race.

Lawrence M. Krauss Quotes