At a time when the strategic threat environment is unsettled, the transatlantic storm has been taking place and the EU takes strategically important decisions about its future, great effort must be directed toward analysis of the fundamental aspects of building new security architectures. A clear conceptual framework must guide such analysis, but no consensus exists on what the core concept should be. The vision of a transatlantic team founded largely on specialization in the security area and incorporating traditional recipes of complementarity and interlocking (limiting duplications and overlaps) seems to have a potential to become the guiding principle for successful transformation of the current framework of transatlantic security cooperation. My paper will inform a larger theoretical examination of the dynamics between power and institutions. After evaluating to what extent are the visions of transatlantic team and security specialization compatible with the current situation in the transatlantic and intra-European relations, this analysis should address questions in three layers. Firstly, to what extent do these visions offer a good and effective solution to structuring a security relationship? Secondly, how can these visions themselves contribute over time to their own acceptability and deepening in the transatlantic area and, more generally, to the transatlantic team spirit building (role of the specialization spiral, TAFTA ? economic pillar of the transatlantic team, the Transatlantic Steering Group)? Thirdly, should both these two parts of the analysis lead to positive conclusions, what are the prospects of these visions being actually adopted at the transatlantic level (the role of New Europe, unsettled security environment and ?EU bureaucracy)? Current context of European and transatlantic security cooperation is approached through the lenses of the transatlantic team and security specialization. The main focus is on dynamic developments in the area of the Common Foreign and Security Policy and European Security and Defense Policy of the European Union. Draft of the EU Constitution, European Security Strategy, April Mini-summit Declaration, December Declaration on European Defense and other strategic documents are examined. Initiatives such as enhanced cooperation, structured cooperation, closer cooperation, EU Rapid Reaction Capability and collective capability for planning and conducting operations are subjected to a critical analysis from the transatlantic perspective. Adequate attention is paid also to current trends in the development of the North Atlantic Alliance. The NATO Response Force receives a particular attention as an important catalyst, paving the way toward the future accommodation of the concept of specialization in the NATO architecture. The identification of policy options that should and should not be chosen in order to enhance transatlantic security relations is inherently present throughout the paper. [ABSTRACT FROM AUTHOR]