“To maintain international peace and security” is the main purpose and reason d’être of the United Nations. From the dispatch of the first UN observers to the Middle East under UNTSO (UN Truce Supervision Organization) in the late 1940s to the deployment of UNAMID (African Union/United Nations Hybrid operation in Darfur) in Sudan in 2007 and UNSM in Syria in 2012, the UN has been involved –directly or indirectly—in tens of peacekeeping operations. Limitations imposed on the UN peacekeeping capabilities during the Cold War because of the superpower rivalries were removed by the end of the era. Unprecedented cooperation among the Security Council members in the early 1990s resulting in the successful (first) Gulf War against aggressive Iraq and a number of humanitarian interventions in “failed” or “rogue” states raised the prospects of active UN peacekeeping role in the increasingly shrinking “global village.” By the end of the decade, however, the UN record in humanitarian interventions caused serious doubts about its institutional capacity to deal with the changing challenges of the peacekeeping. The U.S. unilateralism in its invasion of Iraq in March 2003 put the UN in a much more awkward position. The humanitarian crisis in Darfur, Sudan, and the inability of the international community to take effective measures against an oppressive regime in Syria has raised new questions about the viability of this international organisation. Nonetheless, some positive achievements of the UN in peacekeeping in the past together with the grave need of the international community to act multilaterally to ensure peace and security in a world rife with civil strives and ethnic problems make the UN the only beacon of hope for the future. This course is designed to give students a better understanding of the peacekeeping role of the United Nations. The first parts of the course will discuss the institutional mechanism of the UN for peacekeeping operations, the changing nature of peacekeeping, the legal and ethical issues involved in peacekeeping and humanitarian intervention, and a historical overview of the UN peacekeeping function during the Cold War. Then the course will provide brief case studies of the UN humanitarian interventions and peacekeeping/peace-building operations in the last decade of the 20th century and the first decade of the new millennium in Africa, the Balkans and Cambodia. The United Nations peace efforts in East Timor, Afghanistan and Iraq will be discussed in some detail. East Timor, where the UN assumed the sovereignty, was an unprecedented operation. Afghanistan presents an especially interesting case. The UN has been involved in peacemaking, peacekeeping and peace-building in Afghanistan since the early 1980s; and the UN mission in Afghanistan enjoys overwhelming international support. The UN role in Iraq, from the unprecedented Security Council resolutions in the first Gulf War to the awkward relations with the U.S. in the second, also deserves special attention. Towards the end of the course, we will examine the role of the regional organisations in peacekeeping and the new experiment in “hybrid” peacekeeping.