Weinberger, reached by phone at his home in Maine, says he and Schweizer exchanged manuscript drafts when they were creating the story of Secret Service agent Michael Delaney, who is falsely implicated in the assassination of the president at Camp David. Although Weinberger drew on his almost seven years as Defense secretary, "I didn't want to use any material that is classified. ... I wanted to be sure that I wasn't breaking any laws or pledges."

Chain of Command also details how a series of terrorist attacks create an acceptance of martial law in a nation that always has "prided itself in being an open and free society," Weinberger says.