The purpose of this monograph is to comprehend the reasons that carried the United States, to do not military intervention in Rwanda s Genocide in 1994 and in the post-genocide to justify its inaction sending humanitarian assistance to the country exempting itself of the conflict irresponsibility. From the next questions: Why United States, in the role of Great Power and permanent member of the safety Board of ONU, did not intervene militarmente in Rwanda s Genocide, in 1994? Why, in the post-genocide, did this inaction it manifest by means of humanitarian help? The defended hypothesis is that the USA opted for if do not involve in the conflict of Rwanda, because Rwanda s Events did not translate the north americans national interests that only agreed with the intervention to contain the sequential pressures in international and domestic plan. Stressing that the United States participation it manifested an essentially humanitarian intervention, in other words, starting from an American government maneuver policy, to alleviate the pressures constituting thus a humanitarian alibi. Through the direct manipulation of the determinations of the safety Board using itself of your status to exercise can and influence on the institution, as it foresees the mark theoretician The False Promise of International Institutions de John J. Mearsheimer.