Humanitarian intervention becomes a focal point of international debate because it seems to be morally right but legally wrong. It challenges the principle of non-intervention and non-use of force encompassed in the Charter of the United Nations (UN), which was established in 1945 to prevent aggressions that led to the two world wars. However, since the 1990s, state practices of military intervention to protect human rights increased dramatically, many of which were even endorsed by the UN or in close cooperation with it. In other words, the UN is the most important, or insofar the only acceptable, body to authorize and legitimize any military operations with humanitarian rationale. This research aims at investigating the limitations of the UN in coordinating its responsibilities of maintaining peace and security and of protecting human rights. Two cases, Rwanda in 1994 and Sudan from 2003 on, are chosen as examples to probe into the practice of the UN and try to determine what has changed and what remains steadfast of the UN practice in humanitarian intervention in these ten years. By focusing on the cases of Rwanda and Sudan, this thesis is intended to address the following questions: (1) In the past decade, has the UN system become more comfortable with humanitarian intervention? (2) What are the limitations of the UN in conducting “humanitarian intervention”? What causes these limitations? And why? (3) What can be done to improve the incompetence of the UN in terms of humanitarian intervention? How to harmonize the UN’s conflicting responsibilities of upholding human rights and defending the principle of non-intervention? This research concludes that the new approach of the “responsibility to protect” that was created in recent years shows that a normative change is on the way. Besides, from Rwanda to Sudan, the UN has made progress in addressing grave humanitarian issues. However, all the efforts still have to depend on the political will of the member states of the UN. Since this issue is still more a political one than a legal one, in the years to come, the UN will still face the difficulty of fulfilling its responsibility.

後冷戰時期非洲地區依然存在族群衝突問題，其原因來自於族群地位不平等，以致族群間無法融合。非洲國家若無法建立起「國家利益優先於族群利益」概念，並壓制「部落主義」情緒，則國家內部可能因族群爭權，而陷入長期動亂當中。盧安達種族屠殺及蘇丹內戰和達佛問題等，均係後冷戰時期非洲族群衝突的重要個案，本論文將加以深入研究。國際社會自美國於1993年出兵索馬利亞任務失敗後，對非洲動亂抱持冷漠態度，故造成1994年盧安達種族屠殺慘劇。自此之後，國際社會積極採取有效途徑，解決非洲地區動亂問題，而2004年國際社會積極處理蘇丹達佛衝突，即在避免重蹈盧安達事件的覆轍。本論文將透過後冷戰時期非洲族群衝突個案探討，從中找出非洲族群衝突的根源、影響族群衝突的內外部原因及國際社會介入處理的成效。