For more than two decades, arms control experts have argued that the most likely scenario for the hostile use of nuclear weapons was not between the former Cold War superpower rivals, an act of terrorism by an underground terrorist group, or the periodically threatened unilateral U.S. attack against a “rogue state,” but between India and Pakistan. These two South Asian rivals have fought each other in three major wars—in 1947, 1965, and 1971—and have engaged in frequent border clashes in recent years in the disputed Kashmir region, coming close to another all-out war as recently as 2002.