Future historians contemplating the gravest failures of our day will almost certainly place high on their list the blithe indifference of the major powers, beginning with the United States, to the opportunity after the Cold War to chart a safer course in what remains a nuclear world. Relieved of the pressure to race one another, the nuclear haves could have seized the moment to create what Arbatov and Dvorkin call a "nuclear partnership" or a "mutual nuclear assurance strategy." Not only have they failed to do this, but they have also, with the United States in the lead, dismantled the frail architecture of arms control agreements built during the Cold War. In the process, they have made nuclear weapons more "usable" at a time when these weapons are useless in addressing the core security threats of the day. All this and the alternative path not (yet) taken, Arbatov and Dvorkin, two of the most sophisticated thinkers on these issues in either Russia or the United States, lay out in a simple, lucid, and powerful fashion.