A 2005 RAND Corporation study found the UN to be successful in two out of three peacekeeping efforts . It compared UN nation-building efforts to those of the United States , and found that seven out of eight UN cases are at peace , as opposed to four out of eight US cases at peace . Also in 2005 , the Human Security Report documented a decline in the number of wars , genocides and human rights abuses since the end of the Cold War , and presented evidence , albeit circumstantial , that international activism — mostly spearheaded by the UN — has been the main cause of the decline in armed conflict since the end of the Cold War . The UN has also drawn criticism for perceived failures . In some cases , the Security Council has failed to pass resolutions or the member states have been reluctant to fully enforce them in the face of deteriorating conditions . Disagreements in the Security Council are seen as having failed to prevent the 1994 Rwandan Genocide . UN and international inaction has also been cited for failing to intervene and provide sufficient humanitarian aid during the Second Congo War , the failure of UN peacekeepers to prevent the 1995 Srebrenica massacre , failure to provide effective humanitarian aid in Somalia , failing to implement provisions of Security Council resolutions related to the Israeli – Palestinian conflict , Kashmir dispute and continuing failure to prevent genocide or provide assistance in Darfur
Srebrenica massacre
Srebrenica massacre
History of United Nations peacekeeping