External energy security has gained importance within the EU due to the current Russian-Ukrainian natural gas dispute, but also because of mid- and long-term issues connected to the availability of energy supply in Europe. The Energy Union proposal is supposed to increase the coherence of the EU in external energy, thus contributing to the energy security of the Community. However, various member states have already expressed different (not always positive) views, concerning this project. In order to shed light on the further development of the Energy Union, the present paper based on 52 semi structured interviews examines members states' support for and opposition to the further deepening of integration in external energy security. By analysing Austria, the Czech Republic and Slovakia, this paper argues that member states' preferences depend at least partly on the decision-makers' perceptions of their state's ability to cope with three energy security challenges (external, internal and business). States whose decision-makers believe that their countries are able to successfully cope with these challenges are more likely to oppose further integration in energy security area, while member states whose decision-makers view these tasks as challenging are more likely to support the transfer of competences to the EU. (C) 2016 Elsevier Ltd. All rights reserved.