The paper analyzes normative transformations in the use of force by the Security Council of the United Nations and the way in which the UNPROFOR (United Nations Protection Force) expresses these changes. The growing widespread of the UN human rights regime combined with the increase on levels of moral interdependence among UN member states are at the center of transformations that challenge classical concepts of collective security and sovereignty. First, because of the creation of permanent institutions in which the fulfillment of this regime is debated, since they change State expectations regarding the behavior of other States. Second, for making the access of information concerning human rights violations possible. The way in which the UN acted in the process of disintegration of the former Yugoslavia indicates the occurrence of such transformations. The operation was planned to guarantee the integrity of the people in the region. The main resolutions of the SC regarding the conflict signaled a connection between human rights and the concept of threat to peace in accordance to the art. 39 of the UN Charter. Nevertheless, the member states did not seem inclined to undertake the costs of security operations that would guarantee the respect for such rights. That indicates that the rules favoring humanitarian intervention coexist with limitations derived from the domestic realm of politics. Nonetheless by authorizing the use of force for the protection of human beings, the SC adopted a post- Westphalian interpretation of the UN international security system, redefining the classical concept of national sovereignty.