Euro-British foreign intelligence cooperation through Brexit and Russia’s invasion of Ukraine: Trust and network power in times of crisis

The United Kingdom (UK)’s exit from the European Union (EU) saw no agreement on foreign and security policy cooperation: consequently, this truncated intelligence sharing for external security. Still, the necessity to share information against common threats remains unchanged, as was highlighted when Russia invaded Ukraine in 2022.
This thesis, integrating legal and International Relations perspectives, investigates how the UK’s role in the EU intelligence-sharing network evolved through Brexit and Russia’s invasion of Ukraine. The goal is to understand the extent and effects of these transformations on the network’s ability to respond to external threats. Specifically: how have the Euro-British polities’, organisations’, and practitioners’ relations adapted to these crises? And how well do current intelligence-sharing channels satisfy the parties’ cooperative needs?
This is achieved by conducting a longitudinal network analysis of EU intelligence-sharing in three phases: pre-Brexit, post-Brexit, and after Russia’s invasion of Ukraine. The UK’s changing role is studied in a sociological-relational perspective. By acknowledging the EU intelligence-sharing network as a multilayered series of inter-polity, inter-organisational and inter-personal relationships, this thesis investigates how each cooperative ‘level’ responded to the crises. This highlights the importance of trust in intelligence cooperation and reveals the network’s adjustment to changes through formal and informal cooperative avenues. The legal analysis intervenes on these informal pathways, reflecting on the implications of current Euro-British informal arrangements for intelligence cooperation. This study’s novel data emerges from over 30 elite interviews with former and current intelligence practitioners, diplomats and experts from civil society, from both the EU and UK.
The thesis’ contribution is threefold. Empirically, it reveals the recent changes in the UK’s role in the EU intelligence-sharing network, and how they affected European security. Theoretically, this project sheds light on how intelligence alliances overcome crises, through an innovative approach that delves into specific micro- and macro- cooperative dynamics while subsuming them rigorously in a holistic network perspective. Finally, the thesis offers policy insight for the future of the relationship.