The 1960s were an especially important decade in the history of both NATO and the Cold War. During that decade, the Soviet Union acquired an invulnerable nuclear deterrent of its own. This long-feared development undermined NATO's military strategy of massive retaliation, which had rested on U.S. nuclear dominance over the Soviet Union. As a result, NATO was compelled to look for a new strategy that was better suited to the nuclear age and relied more on flexible response and strong conventional defenses in Central Europe. This study considers to what degree and for what reasons NATO was successful in crafting an appropriate military strategy and fielding the forces required to execute it. The author examines the process of debate that NATO underwent during the 1960s, paying particular attention to the political interaction between the United States, the principal exponent of strategy reform, and its often-recalcitrant West European allies. He then examines the policy outputs of the 1960s — strategy and forces — in relation to the West's evolving security requirements in Europe.