Ronald D. Asmus was one of the first advocates of NATO enlargement in the early 1990s and later served as the top aide to Secretary of State Madeleine Albright and Deputy Secretary Strobe Talbott, charged with implementing NATO´s expansion. Asmus was involved in the key negotiations that led to NATO´s decision to extend invitations to Poland, Hungary, and the Czech Republic, the signing of the NATO-Russia Founding Act, and finally, the U.S. Senate´s ratification of enlargement. With the spotlight on our allies as never before, Opening NATO´s Door is the first full-scale study of NATO´s expansion and modernization after the Cold War. NATO not only survived the collapse of the Soviet Union in 1991, but also became a central vehicle in the effort to build a new Europe whole and free. How and why did this Cold War alliance become the cornerstone of post-Cold War Europe? This book recounts the process by which American diplomats and policymakers, against formidable odds both at home and abroad, implemented some of the most far-reaching changes in U.S. strategy toward Europe in decades and helped create a new security structure for Europe in the twenty-first century. In his conclusion, Asmus addresses NATO´s future in the wake of the terrorist attacks on the United States.