In January 2026, Ursula von der Leyen, President of the European Commission, announced her proposal for a ‘new European Security Strategy’ to encompass the entirety of the European Union (EU). She elaborated that the strategy would aim to collate defence and security knowledge from EU member states, and ensure that geopolitical challenges are addressed appropriately as and when they may arise.
With Brexit now having occurred ten years ago, the United Kingdom (UK) has a complex relationship with the EU. However, as a custodian of the North Atlantic Treaty Organisation (NATO), and one of the two European nuclear powers, it nevertheless has interests in terms of upholding continental security. With this in mind, for this week’s Big Ask, we asked four experts: How should Britain engage with the new European Security Strategy?
Professor of International Security and Co-Director of Security Research Institute, Lancaster University, and Visiting Fellow, Royal Navy Strategic Studies Centre
The UK should treat the forthcoming European Security Strategy as an opportunity to build structured naval cooperation around shared interests in the maritime domain: defence of the continent, stability of the global maritime supply chain, and protection of critical maritime infrastructure, especially undersea cables and other maritime assets essential to economic and national security.
Building on the EU’s revised Maritime Security Strategy of 2023, which explicitly targets sub-threshold and cyber threats to maritime infrastructure and seeks stronger coordinated presence, exercises, and naval operations, Britain should pursue a pragmatic, mission‑led partnership that complements NATO through targeted cooperation where it adds operational value – particularly in infrastructure protection.
Von der Leyen has stressed that security in the High North is ‘first and foremost’ a NATO responsibility. Here, the UK can add value and increase European credibility by using the Joint Expeditionary Force (JEF) and bilateral cooperation with Norway to help integrate EU member states’ efforts in maritime situational awareness, Anti-Submarine Warfare (ASW), undersea cable protection, and resilience planning, while strengthening links to Baltic and North Atlantic priorities.
Britain should position the EU as a partner of choice for undersea cable security. This can be achieved through the alignment of EU regulatory and coordination tools with the UK’s operational capabilities, intelligence, and rapid response capacity. This would be especially prudent as EU doctrine increasingly emphasises safeguarding undersea infrastructure and maritime domain awareness in the Baltic, North, and Mediterranean seas and Atlantic approaches.
Finally, as the current situation in the Strait of Hormuz underlines, if Britain desires credibility as a defender of a rules‑based maritime order, it needs reliable partners for sustained presence and freedom of navigation missions and for rapid coalition responses to coercion below the threshold of war. This is clearly an area where UK-EU cooperation can multiply effect.
Associate, Walker Morris LLP
The new European Security Strategy reflects an overdue recognition that the EU should assume greater responsibility for its own security. Yet, while the strategy emphasises ‘independence’ and industrial self-reliance, it risks overlooking an essential truth: European security cannot be delivered by the EU alone.
Britain remains central to any credible European defence architecture. A decade after Brexit, the UK and EU are strategically aligned but institutionally distant. This matters. The new strategy’s focus on strengthening defence industrial capacity, accelerating procurement, and scaling innovation depends on capabilities that are already deeply integrated across European supply chains.
Britain is a major contributor across all three dimensions: a leading defence industrial base, a nuclear power, and a cornerstone of NATO. Excluding it from the new European Security Strategy’s industrial and capability building mechanisms would not enhance European autonomy; it would fragment it. Duplication of effort, reduced economies of scale, and weaker interoperability would follow. The EU’s ambition to act more decisively in a more hostile security environment would, paradoxically, be undermined.
Strategic autonomy should not be confused with strategic isolation. If the new European Security Strategy is to deliver meaningful deterrence, it should be built around a broader ‘European-plus’ framework which recognises the UK not as a third country, but as a critical partner. For Britain, engagement should therefore be proactive and structured, ensuring that it helps to shape, rather than react to, the continent’s evolving security architecture.
International Fellow, Council on Geostrategy, and Assistant Professor of International Relations, University of Waterloo (Canada)
Having decided to leave the EU, the UK can, at best, play an indirect role in the formulation of the new European Security Strategy. Nevertheless, it has now been a year since Britain and the EU signed their security and defence partnership. That framework document outlined multiple issue areas where the two sides could develop their cooperation.
The UK shares many common interests with the EU in terms of defending critical infrastructure, repelling foreign interference, and building capacity so that NATO allies can use EU funds to reach their capability targets. These common interests allow for the EU and NATO to build complementarity at a time when continental security is under significant geopolitical duress.
Yet, military mobility is the element that deserves special attention, not least since Britain has been invited to participate in the Permanent Structured Cooperation project in 2022. Despite much ink spilled on the subject in the last decade, significant logistical and regulatory barriers remain in place across the EU, which would hamper the flow of military personnel and equipment in the event of an acute security crisis.
Military mobility thus matters for ensuring that European nations can both defend themselves and support their own sustainment, especially when the UK and the United States (US) are positioned along NATO’s eastern flank. Britain should join PESCO to advance shared goals in improving military mobility across the continent.
As the European Commission drafts its new Security Strategy, the UK can do something militarily advantageous on the continent that still respects its decision to withdraw from the EU.
Melania Parzonka
Research Fellow, Polish Institute of International Affairs
The political alignment on security between Britain and the EU already exists: willingness to support Ukraine, recognition of Russia as a direct threat, and the urgency of rearmament.
Yet, after Brexit, the UK has been left out of seismic developments happening in EU security planning, such as rethinking of the mutual security clause (as an alternative to NATO) or joint borrowing to fund rearmament. With ongoing debates about sources of funding to deliver the aims of the Strategic Defence Review, the latter option especially would be hugely beneficial to a fiscally constrained Britain.
There are, however, other avenues for cooperation. The niche that the EU has carved out for itself on military and defence topics is in the industrial sphere. It has positioned itself to oversee and accelerate European rearmament, as well as foster cooperation between national defence industries. Hence, industry is the area where the UK can prove itself indispensable to the EU.
It is crucial that Britain’s industry can supply armaments to Ukraine under the newly approved €90 billion (£77.8 billion) Ukraine Support Loan. This will anchor the UK in EU-coordinated procurement frameworks and give a precedent for closer cooperation in future programmes. Furthermore, Britain should seek joint industrial projects with like-minded EU member states – for example, NATO eastern flank states, currently the biggest spenders in the alliance on defence as a percentage of Gross Domestic Product (GDP).
The UK has already made a step in this direction with the upcoming British-Polish defence treaty – the third agreement of this kind after ones signed with Germany and France in 2025.
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