The theory of Mutually Assured Destruction has worked well in preventing nuclear war, but there were always issues with it. For example, a flock of geese on the radar could be mistaken for incoming missiles. Other issues, sometimes mentioned, were that a country with nuclear weapons might be ruled by a madman who didn’t care about the future of the globe, or a stupid ruler who didn’t understand the consequences of nuclear war.
Never did I think the madman or the stupid ruler would be the President of the U.S. I couldn’t even comprehend that a President would somehow manage to be a stupid madman. Yet here we are.