NATOs military interventions in the Balkans have transformed the alliance. As the alliance goes East, its members are compelled to rethink NATOs, and each member nations, military and political roles. Providing a wellrounded study of continuing change in the contemporary North Atlantic Treaty Organization, this book is constructed around eight essays by European security experts analyzing challenges confronting the Atlantic Alliance as a military alliance and as a collective security organization dealing simultaneously with deterrence, enlargement, and regional crisis intervention. It is intended for senior undergraduate and graduate students in international relations, American foreign policy, European studies, security and strategic studies.The evidence is that NATO will undergo many more changes responding to actual and potential threats to Europes peace. These range from a revival of the ethnic conflict in the former Yugoslavia to the proliferation and possible use of nuclear, biological, and chemical weapons. Also discussed is the matter of NATOs further enlargement and the question of whether this offers more or less security to the alliance membership, as are the emerging tensions between the EU and NATO security regimes.