Book excerpt: ​This book explores the multilayer nexus among inter-related international and regional security parameters that critically define the EU’s rapidly changing security environment. In terms of intensity, complexity and urgency these changes constitute challenges that threaten the very core of European security – both internal and external. In a fluid and transitional international environment of diversified needs and polymorphic threats the space dimension acquires a novel unified meaning. The book closely examines the EU’s current strategic, organisational and defence capabilities regarding global, regional and domestic challenges such as terrorism, systemic instability, global order and a number of crucial hindrances to transatlantic cooperation. The chapters offer not only valuable theoretical insights, but also unique perspectives on operational and organisational elements of EU applied policies based on the testimonies of field experts. The combination of theory-based approaches and the demonstration of the EU’s operational capabilities and weaknesses as externalized through its global strategy choices provide an overall evaluation of adopted policies and their effects. This is crucial in a global transition period that will define the EU’s role and its potential to produce desired outcomes through synergies with its strategic allies.