person he considered unstable donald trump didn't start a nuclear war unchecked. with me is fred caplan author of "the bomb, president generals and the secret history of nuclear war." i want to talk about the nuclear process, fred, specifically and this is something you write on. what exactly, based on the reporting now from the book which you and i have both read at greater length than some of the articles about it, what did milley do to inject himself into that nuclear process? >> there's been hype about this both in the book and the press coverage of the book. let me just say very quickly how the nuclear process works because most people don't know this. the president doesn't have a button that he pushes. somebody comes in with a big briefcase and has communications gear and code books. he sends a message to something called the national military command center in the pentagon headed by one star general. he authenticates that, yes, it's me. here is my proof that it's me