This article focuses on the security approach of the Western Balkan countries in the frame of the European Union accession. By implementing new criteria to the perspective of accession for a better stability and security in the region, the politics of EU succeeded to promote the regional dialogue between States, 20 years after the tragic conflicts that traumatized the ex-Yugoslavia countries. Last accession of Croatia to the EU shows that progresses have been made for the compliance with EU rules. But even if we can see very important progress in term of security such as border conflicts and ICTY participation, some issues like organized crime and corruption continue to trouble the region especially in the two "international protectorates", Bosnia and Herzegovina and Kosovo. The analysis of these two countries show the limits of the accession perspective impact and reveal difficulties to implement and follow European rules in States headed by ethnic tensions, inefficient fight against local threats, and marked by uncertain future.