A European energy market cannot be achieved without an external energy policy securing energy coming from abroad. A trade-off may arise between the necessity to secure energy supply through intergovernmental agreements with third countries and compliance with Union Energy Law. Therefore, EU policy-makers have to face the dilemma of reconciling the completion of the internal energy market with security of energy supply. This paper argues that this compromise is unlikely to emerge because the Commission and the Member States are driven by divergent interests. Looking at recent legislation, the preliminary results of this research show that while the Commission strives for a European level approach, Member States prefer protecting their bilateral relations with third countries. This divergence challenges coherence between the internal and external dimension of the EU energy policy.