The historical way of development of integration processes in the defence sphere, starting with the end of World War II up to nowadays, appeared to be rather complicated. The European development shows, that security and defence can be provided only by successful activity of different international blocks and organization. The main preconditions and tendencies, investigated in this article, are the basis for the further development of European security system. The investigation of European Unity members evolution of cooperation in the defence sphere gives the opportunity not only to state the main stages of such cooperation and its features on the contemporary level, but to make a forecast of its future development, taking into consideration the challenges the European Union faced with during the last years. Among the most important preconditions for generating and formation of the European state-members cooperation in the defense sphere, the following must be underlined: the demand of peace and security, the aspiration for economic development and welfare and keeping of economic and political significance on the international arena. Proceeding from these preconditions and tendencies the European Union is widening nowadays and will widen further its own defence system. At the same time the new challenges and threats appear. The European society has to identify them and create its effective law and institutional means to resist them. Because of the great number of threats the achievements in the international security system effect become the main task for all peoples. It is quite clear that none of the states nowadays can independently provide its own security against contemporary challenges and threats, without the international help and collective security structures. It must be stressed (underlined) that the greatest number of contemporary challenges and threats for international security need now, and first of all non-military ways of solution for their decision