Change in the international security system: Rise of the collective intervention doctrine

United Nations collective security system is the most comprehensive security arrangement that the mankind has achieved to establish so far in order to ensure international security. Collective intervention doctrine is however the most important order establishment instrument of this security system. As it is the case in all fields of the life, rapid change in the international security environment compels the international security system as well as the collective intervention doctrine to transform.In this regard, while aiming to underline the main elements of the change in the international security system after the Cold War, this thesis tries to analyze the evolution of the collective intervention doctrine which constitutes the visible side of the adaptation to the change of the collective security system and touches the increasing role of the United Nations as well as the EU and NATO in the context of international crisis management.In contemplation of the assessment of the change and transformation in the security system is possible by examining the changes and differences in the implementation of the collective intervention doctrine and moving from this basic institution, the thesis intents to read the whole of the system. With this understanding, during the course of the study, various examples of collective intervention are dealt with and the widening of the definition of both the self-defense institution enacted in the article 51 of the Charter of the United Nations and act of attack are duly drawn attention.