The Nevada Proving Grounds after a test detonation, 1953.(Courtesy National Nuclear Security Administration/Nevada Site Office)

When the Soviet Union fell and the Cold War was declared over, most people happily forgot that tens of thousands of nuclear warheads were still poised to go off at a moment’s notice. Ron Rosenbaum is less complacent; he has become obsessed with the persistence of the threat of a nuclear attack, whether purposeful or accidental. (Nine countries have roughly 20,000 nuclear warheads, according to the Brookings Institution, and that figure accounts only for those weapons of which there is a record.) It’s a likelihood that is growing as unstable regimes race to acquire warheads of their own, he argues in his new book, How the End Begins: the Road to a Nuclear World War III, in which he examines the extent of this threat and looks for ways to resolve it. He spoke to Vox Tablet’s Sara Ivry about the obsolescence of deterrence in our geopolitically unstable world, the close calls in the history of the nuclear age, and the prospect of realizing President Barack Obama’s goal of eliminating nuclear weapons. [Running time: 16:55.]

Read an except from How the End Begins here.