The European Union, which is a regional integration organization, has been able to develop several security policies, this was possible thanks to several factors. The attribution of competences to the Union constitutes the 1st factor which enabled it to act not only within the interior but also at the international level and we have seen the examples where the priority of action is granted to the EU which is a factor in strengthening its security policy. Consistency is not only a principle structuring the division of tasks between the institutions of the Union but also organizing its relationship with its Member States and the rest of the world and affecting the very essence of its action in the security field. , as an international player. The treaties have also given it exclusive external competences, blocking any possibility of counter-action by the Member States bound by an obligation of loyal cooperation. The Union is often faced with several challenges, traditional and modern, but with an effective CFSP/CSDP, it could act decisively to ensure international peace and security, while maintaining the coherence of its external action.