FRESH AIR: Our guest Daniel Ellsberg became one of the best known opponents of the Vietnam War in 1971 when he leaked the Pentagon Papers, a secret Defense Department study of the war, to The New York Times and other publications. Ellsberg, then a national security analyst with top-secret clearances, was arrested and tried under the Espionage Act. A judge dismissed the charges when it emerged that officials in the Nixon administration had directed covert actions to discredit or silence Ellsberg, including tapping his phone and breaking into his psychiatrist’s office, looking for compromising information. Ellsberg is now 86, and he has a new book about his days before he studied the Vietnam War when he worked on American nuclear war strategies in the late 1950s and early ’60s. Ellsberg was appalled by much of what he found and wishes he’d been able to leak those plans along with the Pentagon Papers. Daniel Ellsberg is the author of a 2003 memoir about the Pentagon Papers and Vietnam called “Secrets.” He’s also the subject of the Oscar-nominated documentary “The Most Dangerous Man in America.” And he’s a character in the forthcoming Spielberg film about the Pentagon Papers, “The Post.” FRESH AIR’s Dave Davies spoke to him about his new book, “The Doomsday Machine: Confessions Of A Nuclear War Planner.” MORE