The sudden transformation of the Cold War security order in 1989 altered the structure of the European state system, and necessitates the striking of a new balance between the economic, political and military requirements of security. This volume focuses on the most important institutions of European security, the European Union and NATO. Both institutions are expanding, especially eastwards, in terms of their respective roles and membership. This double expansion raises many questions; most crucially, whether Europe will be a two-speed security order, which suggests openess, inclusiveness and the emergence of an anarchical society, or a two-tiered security order, which suggests a continued hierachical security system with all of its associated historical liabilities.