Since the end of the cold war a lot of things have changed in the international relations in the entire world. The profound changes initiated a process of transformation both in NATO and EU. The tragic events of September 11th had a further strong influence on the desire of both organizations to adapt to the new environment. Meanwhile the relations of these two most important organizations of the political West have been the subject in the center of many analyses. In essence, the end of the Cold War profoundly changed the central parameters of the relationship between Europe and the US. The developments in the Western Balkans have been very important in shaping the EU-NATO relations to be more defined. The following paper will examine the Integration process of Western Balkans and under the influence of transatlantic relations. There need to be wholehearted, unambiguous European adherence to the principle of "where NATO as a whole is not engaged, " and political processes should be developed to ensure that no doubts arise about this point or about NATO's ability, sufficiently early in a crisis, to make such a determination. Many Europeans will resist the notion that this implies "NATO first": But as a practical matter, it is important for preserving cohesion of the alliance. Securing this goal, which is important to the United States, will probably have to come from day-to-day consultations, including close cooperation between the North Atlantic Council, the EU's Political and Security Committee, and permanent, day-to-day liaison arrangements between the two; but it requires a shared vision and political commitment on all sides.19 In short, US reluctance to share the risks and tasks, especially in the Balkans, the most serious area of instability in today's Europe, would be incompatible with the effort to keep the Security and defense policy of EU (ESDP) as simply a second-choice option for dealing with crisis and conflict in Europe.