Return to Europe? Institutional choice, outsider status, and Britain’s response to the Ukraine War

The European response to Russia’s invasion of Ukraine is characterised by an emerging division-of-labour between NATO and the European Union (EU). By reducing the substitutability of organisational frameworks, this makes life more difficult for outsiders – like the post-Brexit United Kingdom – which find themselves on the outside of key decisions. Drawing on interviews with policymakers, this article shows how Britain has engaged with EU security policy following the Ukraine War. It shows how the EU/NATO division-of-labour undermined the viability of Britain’s post-Brexit break with EU security policy and brought about a concerted effort to engage from the outside, including efforts to lead by example, establish new frameworks, and coordinate through informal channels. The findings help explain how seismic events can shape institutional choice and thus the costs of remaining on the outside, and they showcase the diversity of means available for external engagement.