Oleksandr L. Common policy of the European Union in the sphere of security and defense under conditions of its expansion.

The dissertation is dedicated to the study of the modern dynamics and perspectives of Common European Security and Defense Policy (CESDP) development under the conditions of the EU expansion eastwards and in the Mediterranean region. The theory and the concept fundamentals of the CESDP were outlined and the major factors of its formulation and evolution under conditions of the EU expansion were detached and systematized in the present work. At the same time, it was determined that the CESDP naturally combines characteristics of the "traditional" systems of collective defense and international security, but can be classified as none of them. The latest expansion of the EU has stimulated an evolution of the CESDP which runs under the influence of a number of objective and subjective factors. The influence of the objective factors is connected with the creation of the new balance of powers in the world resulting from a considerable growth of the EU membership in 2004 and expansion of its borders. The influence on the CESDP development of the subject factors is conditioned by the peculiarities of its implementation by the "old" and "newly accepted" members, as well as the nature of the EU security interaction with the states that have not yet joined the union - the co-called "third" states. There was defined in the dissertation that the divergences in the approach of different EU member-states towards the CESDP are to be explained by the existing peculiarities of their security characteristics, historical experience, strategic culture and world outlook, geopolitical and military-political thinking. The author has also proved that a scheme of the EU security cooperation with the "third" states depends on the role and place of the each of them in the international security system and other foreign policy and defense characteristics. There was also explained a dual role of Ukraine in the context of the CESDP implementation by the European Union - both as the potential source of challenges and as crucially important for the EU security partner in Eastern Europe.