Some do not suspect how dangerous Donald Trump can be for the world. He has demonstrated until now that he is a self-centered unbalanced person, capable of the worst excesses. What is currently very worrying is the fact that he has surrounded himself with pro-war generals (Kelly, Mattis, McMaster, Dunford Jr. etc.), trained to obey a civilian commander whatever the orders.
What will they do if Trump asks them to bomb North Korea or China with nuclear bombs? These generals occupy ministerial posts normally headed by civilian ministers to supervise the military.
With them, Trump can behave like a dictator and give them orders they are supposed to obey. On his own, Trump could plunge the world into a nuclear war. Secretary of State Rex Tillerson can easily be outvoted, and the U.S. Congress would then be his only check. This is not very reassuring.