The Democratic Republic of the Congo (DRC) is a country with the most prolonged rebel conflict of the 21st century. This thesis analyses the causes of the UN's difficulties in finding a solution to the crisis of rebel groups that threaten security in the DRC, particularly in its eastern part. Most of the existing work on the subject under study states that peacekeeping missions' failure in the DRC is due to various factors such as mandate, strength, complexity of violence, etc. However, existing studies have not analysed the work of MONUSCO as a regime and why this regime is ineffective. In approaching the theory of the international regime, this study uses the internal and external factors of the regime to analyses the causes of this ineffective peacekeeping mission in the DRC. The research applies qualitative methods with primary and secondary data obtained from official MONUSCO documents, books, journals, and online news. This study shows that the rebel crisis in the DRC is due to various internal problems. In addition, MONUSCO principles and rules are ineffective in eradicating the rebel groups, which cause insecurity, deterring peace in the DRC.