This RAND study examines the potential defence and security implications of the UK's decision to leave the EU. Specifically, it seeks to identify those policy areas, strategic concerns or military capabilities that might be most affected, as well as the spectrum of possible outcomes. The goal is to help policymakers to understand the key questions provoked by Brexit, and thus how they begin to plan for, mitigate and address these uncertainties.

Defence and security after Brexit

Understanding the possible implications of the UK's decision to leave the EU — Compendium report

James Black, Alexandra Hall, Kate Cox, Marta Kepe, Erik Silfversten

ResearchPublished Mar 5, 2017

This RAND study examines the potential defence and security implications of the United Kingdom's (UK) decision to leave the European Union ('Brexit'). Specifically, it seeks to identify those policy areas, strategic concerns or military capabilities that might be most affected, as well as to explore and define the spectrum of possible outcomes in each area. The goal is to help policymakers both inside and outside the UK to understand the key questions provoked by Brexit, and thus to inform how defence and security actors begin to plan for, mitigate and address these uncertainties as the UK begins negotiations to leave the European Union.

This RAND study comprises three publications:

  1. This compendium report, which provides the greatest level of detail on the analysis conducted.
  2. The associated overview report, which outlines the principal findings of the study.
  3. A standalone international perspectives report, which provides a snapshot of selected international perspectives on Brexit following the June 2016 referendum.

Key Findings

International cooperation

  • Defence may be less immediately affected by Brexit than areas such as labour policy or trade. Much international defence cooperation takes place through NATO or bilaterally — as will remain the case after the UK leaves the EU.
  • Analysis highlights the need for sustainable post-Brexit solutions for defence and security. This will require effective compromise and continued engagement between the UK and EU, which have both benefited from information-sharing, the joint work of bodies like Europol, and use of the European Arrest Warrant.

Strategic ambitions

  • Nonetheless, Brexit will require that both the UK and EU re-evaluate their strategic goals, what role they want to play in the world, and whether they have the capabilities and collaborative frameworks needed to achieve them.

Future of EU defence and security

  • The loss of the UK is a significant loss for the EU on defence. Some estimate that Brexit could reduce the EU's defence capabilities by a quarter. EU leaders are now working on plans to promote more EU defence integration, perhaps through a European operational headquarters — a plan long blocked by the UK while an EU member.

Regional implications

  • There are also important national and regional complications. France and Spain, for instance, are likely to reassess border relations at Calais and Gibraltar. For the UK, there are unique concerns facing Northern Ireland and Scotland.

Integrating defence and security into Brexit negotiations

  • Unlike in some other areas of policy, the UK is seen as a net contributor to European security and defence. This raises difficult questions for both sides about whether, when and how to leverage this in wider Brexit negotiations. Both sides risk becoming weaker and less secure if Brexit talks provoke a 'zero-sum' approach and messy divorce.

Topics

Document Details

Citation

RAND Style Manual
Black, James, Alexandra Hall, Kate Cox, Marta Kepe, and Erik Silfversten, Defence and security after Brexit: Understanding the possible implications of the UK's decision to leave the EU — Compendium report, RAND Corporation, RR-1786-RC, 2017. As of October 4, 2024: https://www.rand.org/pubs/research_reports/RR1786.html
Chicago Manual of Style
Black, James, Alexandra Hall, Kate Cox, Marta Kepe, and Erik Silfversten, Defence and security after Brexit: Understanding the possible implications of the UK's decision to leave the EU — Compendium report. Santa Monica, CA: RAND Corporation, 2017. https://www.rand.org/pubs/research_reports/RR1786.html.
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Research conducted by

Funding for this study was provided, in part, by donors and by the independent research and development provisions of RAND's contracts for the operation of its US Department of Defense federally funded research and development centers. The study was conducted through the Defence, Security and Infrastructure programme at RAND Europe as well as through the International Security and Defense Policy Center, which is part of the RAND National Defense Research Institute.

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