The Turkish candidacy to European Union points out the question of the origins, the future and the security construction of EU. Through the studies of past and actual parameters of the defense and security common policy and also regarding the involvement of Turkey in the construction of EU defense policy, this thesis proposes an analysis of the politic and military cooperation's between Turkey and EU members from 1945 until today. The Turkish and the European visions of European and international security might converge or diverge somehow, but our aim is to determinate the challenges, the needs, and the lacks of their partnership in order to draw a compatible frame according to the recent changes of the international scene. The Constructivist approach highlighted in this thesis, invites the reader to understand the European project of security as designed by the internai and external feedings and perceptions to the European project. Taking into account the past common initiatives, and keeping in mind the feedbacks related to the needs of both Common Security and Defense Policy and Turkish security system; it seems obvious to question ourselves on the benefits of the enlargement to Turkey for the EU security policy (1). It appears possible to understand the future dimension of European and Turkish policies, but also to appreciate their potential impact on the global order, by the analysis of the several European apprehensions and the political evolution of Turkey (II).
