Although the threat of terrorism was one of the driving factors behind the initiation of internal security cooperation among European states in the 1970s, the European Union (EU) only began to develop its counter-terrorism policy following the terrorist attacks against the United States on 11 September 2001 (Argomaniz 2011; Bossong 2013; Kaunert 2010c). The realisation of the transnational scope and the multifaceted character of the terrorist threat led to an increase in the political will to cooperate among EU Member States, which had been previously rather limited (Kaunert 2010b; Mahncke and Monar 2006; Spence 2007). The bombings in Madrid in 2004, and in London one year later, led to a deepening of the cooperation among EU Member States, epitomised by the establishment of the position of an EU Counter-Terrorism Coordinator in March 2004 (Council of the European Union 2004: 14) and the adoption of the EU Counter-Terrorism Strategy in November 2005 (Council of the European Union 2005). The bombings also resulted in increased counter-terrorism cooperation between the EU and third countries, as policy-makers increasingly acknowledged the strong transnational dimension of the terrorist threat faced by European states (Kaunert 2010a). The EU Counter-Terrorism Strategy of 2005 emphasised the importance of ‘[combating] terrorism globally’ (Council of the European Union 2005: 6). This trend has not been confined to the realm of counter-terrorism, but has characterised the EU’s security policies generally. As the linkages between internal and external security have been reinforced, European leaders have repeatedly asserted the necessity of mobilising all the tools at the EU’s disposal to tackle internal threats, including in the neighbourhood (Ioannides 2014). One of those has been the European Neighbourhood Policy (ENP).