Table of Contents: I. Introduction. – II. Post-Brexit security and defence cooperation as differentiated disintegration – III. Theresa May and the proposed “security partnership”. – IV. The trade and cooperation agreement and beyond. – V. The war in Ukraine: A game changer? – VI. Conclusion.
Abstract: Research on differentiated integration has flourished in recent years, highlighting the political and efficiency gains to be had from selective participation and third country engagement in EU policy areas. Proposals for an EU-UK security and defence agreement represented a paradigmatic example of differentiated disintegration, for which both strategic and political prospects initially appeared positive, yet which ultimately foundered on the back of the EU’s reluctance to create new third country models and subsequent political upheaval in the UK. This Article asks why these proposals failed and what this can tell us about the politics of differentiated (dis)integration, focusing on the referendum to the recent Ukraine crisis, and drawing on several elite interviews conducted with policymakers in London and Brussels. It shows that while the strategic benefits of differentiation increased following the Brexit vote, the growing concern in Brussels for the precedent set by Brexit, the collapse of issue-specific dynamics into a singular concern for UK “cherry picking”, and the rightward shift in UK politics occasioned by the Brexit negotiations all undermined the prospects for a differentiated outcome in security and defence. The Ukraine crisis, while precipitating significant changes in many European states, had thus far failed to alter the new status quo locked in after Brexit.
Keywords: Brexit – differentiated integration – Ukraine War – European security – EU-UK relations – United Kingdom.