There are moments in the evolution of U.S. foreign policy where think tanks have had a decisive influence in reshaping conventional wisdom and setting a new course on a key strategic issue. The debate over NATO enlargement in the early 1990s was one of those moments. U.S. think tanks played a key role in developing and building support for the U.S. decision to enlarge NATO as part of a broader strategy of overcoming the continent’s Cold War divide and building a Europe whole and free and at peace. It was a dramatic period. The collapse of communism in Central and Eastern Europe in 1989, and the disintegration of the Soviet Union itself two years later, had also left in its wake a vacuum in terms of Western policy in the region. The democratic revolutions of 1989 in Central and Eastern Europe had taken the West largely by surprise and, as welcome as they were, they nonetheless overturned many of the underlying assumptions that had previously guided Western thinking and policy. Events on the ground were outpacing the ability of many policy-makers to rethink their paradigms. Western governments and bureaucracies were at times behind the curve of history—and they knew it—victims, in a sense, of our own success. Having succeeded in toppling communism without a shot fired in confrontation between East and West, the West was unprepared politically and intellectually to produce a new vision of what kind of post-Cold War Europe and trans-Atlantic relationship was needed for the future. What was NATO’s purpose in a world without communism and a Soviet threat? These questions produced one of the most passionate and divisive foreign policy debates of the 1990s in the U.S. The issue was not only whether or not to enlarge NATO to include Central and Eastern Europe, a question that was in many ways just the tip of the iceberg. Policy-makers were also battling over nothing less than what kind of Europe and U.S.-European relationship the United States should build for the new era. The result was some of the most far-reaching changes in U.S. and NATO strategy in decades. I was fortunate to have a bird’s-eye view of this debate, first as a RAND analyst, subsequently as a deputy assistant secretary of state in the European Bureau, and later as a senior fellow at the Council on Foreign Relations. Why did think tanks play such a key role in this debate? There were several reasons. First, in the early 1990s there was a keen demand for fresh and outside-thebox thinking on both sides of the Atlantic, and governments were often not well