The European Union currently faces a number of unprecedented security challenges. Conflicts at every border of the Union, failed states and the growing presence of transnational terrorism are just a few examples. Recent events in various European capitals show that it is not possible to distinguish between internal and external security, and that international borders do not deter threats. Despite this, Europe’s response to these events has mainly taken place at the national level. Moreover, the European Union’s budget for defence and security is significantly smaller than its budget for other policies, and the collaboration of the Member States is very limited, resulting in inefficiencies and duplications. [...]