Executive Summary

• Donald Trump's re-election has heightened the UK's desire for a new EU-UK security pact to enhance defence cooperation.

• The UK's exclusion from key EU defence initiatives risks isolating it from European strategic planning.

• Due to sovereignty concerns, EU-UK defence cooperation will likely rely on ad-hoc agreements rather than full integration.

• The EU's differentiation between members and non-members challenges offering the UK preferential defence collaboration without compromising EU principles.

• Uncertainty over NATO under Trump's leadership prompts the UK and EU to explore alternative security arrangements.

• Formalising EU-UK security relations through a new pact is recommended, focusing on intelligence sharing, joint procurement, and strategic coordination.

The election of Donald Trump only revived the Starmer government's expressed desire for greater EU-UK cooperation. In his few months in power, the new prime minister has already desired a new UK-EU security pact to replace the current framework. This review will analyse how EU member states perceive the UK as an ally and how negotiating and ratifying this pact might affect this relationship. To do so, one must first briefly explain the current state of EU-UK cooperation concerning defence. The Trade and Cooperation Agreement signed in 2020 did not mention UK participation in joint European defence endeavours. As a result, projects like the Permanent Structured Cooperation and the European Defence Fund have become central aspects of member state’s defence planning when UK firms are completely excluded. The risk for the United Kingdom resides not only in the missed opportunities for defence firms but also in the gradual exclusion of the UK from any strategic planning on the continent. Indeed, the risk is that the EU will become the main forum where member states discuss defence, a risk that has become salient due to the fears caused by Donald Trump’s re-election. 

Issue Identification

Peace in Europe is the objective that led to the creation of the European Economic Community and lies at the heart of the EU. Along with economic integration, especially the integration of resources used for war-making in the 1956 European Coal and Steel Community (ECSC), Defence integration was the second pillar in this endeavour. European leaders sought the creation of the European Defence Community (EDC), effectively creating a European Army. However, in 1954, the referendum on establishing the European Defence Community failed in France, ending this stream of integration for decades. 

Surprisingly, the United Kingdom was one of the leading actors in constructing European foreign policy and defence for some. Indeed, a bilateral summit between Jacques Chirac and Tony Blair in Saint-Malo proposed the idea of transferring the responsibilities of the Western European Union to the EU, directly leading to the creation of the ESDP (now CFSP/CSDP). Since 2016, the EU has become an important factor in European defence by facilitating production and procurement between member states. This role is based on the assumption that member states share strategic objectives and interests in European Security. The problem for the UK resides in the fact that it is a major actor on the world scale and outside the EU institutions; it shares the same strategic interests as EU member states but has no say in policy-making in Brussels. 

The basis for any cooperation, as laid out by the UK government in 2018, is that any effort needs to respect the UK’s sovereignty and the EU’s decision-making autonomy. (HM Government 2018). That is to say, cooperation can only occur when no EU institution has decision-making power over the UK, and the UK cannot participate at the same level as member states in decision-making. As a result, cooperation seems destined to occur through ad-hoc agreements rather than the UK joining existing EU structures. The presence of UK Foreign Secretary David Lammy at an EU Foreign Council meeting concerning Ukraine and the Middle East is a sign that this cooperation is likely to occur on a case-by-case basis. The Trade and Cooperation Agreement also established dialogue structures concerning cyber security and counter-intelligence. 

The priority of the UK is to grow its influence within NATO and its bilateral relations with the United States. Any effort to cooperate with the EU requires compatibility with that objective. While NATO has generally been positive towards EU defence cooperation, certain efforts, including joint-procurement, have been pointed out as rivalling that of NATO. However, the importance of this factor in EU-UK cooperation depends greatly on the approach that Donald Trump will take in the first months of his presidency. The choice of Marco Rubio as his secretary of state complicates this question as Rubio shares a traditional neo-conservative approach to foreign policy. Still, his statements about Ukraine or European freeriding in defence within NATO are far from reassuring for Downing Street and Brussels. 

Key Challenges

From the European Union’s perspective, UK participation represents a bit of a dilemma. As Polish Foreign Minister Radosław Sikorski said, it is ‘in the DNA of the EU […] to differentiate between members and non-members.’ Given that most of the narrative surrounding Brexit in Brussels consisted of opposing the UK ‘cherry-picking,’ it seems unlikely that the UK can expect any type of preferential treatment compared to other non-member states. Additionally, some of the most beneficial aspects of cooperation with the EU, such as access for British firms to funds such as the European Defence Fund (EDF) or the Act in Support of Ammunition Production (ASAP) seem highly unlikely given the lack of contribution of the UK to EU funds. Other funds, such as the newly unveiled procurement-focused EDIRPA require projects with at least 70% involvement of EU-MS. 

For the European Union, the election of Donald Trump is a clear sign that NATO alternatives may become necessary in the short term. Currently, Brussels is considering redirecting a part of the unused cohesion funds, usually used to reduce economic equality, to defence. This initiative is accompanied by numerous declarations from national politicians appealing for greater initiatives on the EU level in this field. What this means for the UK is that it needs to show strong signs of commitment to cooperation with the EU, not to be stuck in between a potentially dying NATO and the EU with neither able to provide it with the security guarantees Downing Street requires.

Recommendations

With this new security pact, the UK can take multiple paths to create mutually beneficial relations with Europe. The first step is formalising cooperation to depart from current efforts that are mainly ad hoc. A new pact is the path to this formalisation. That being said, the 2026 review of the Trade and Cooperation Agreement also offers another opportunity to formalise this relationship, potentially accompanied by greater debate within the public sphere. Below are a few fields that provide potential for the UK or its defence firms. 

Intelligence: The European Commission tasked Sauli Niinistö (Former president of Finland) with reporting on the EU's readiness for war. His paper concluded that the EU required a “fully fledged intelligence cooperation service,” which newspapers compared to a European CIA. The UK is particularly well-equipped in terms of intelligence and could share its experience with the EU. Additionally, the UK lost its access to the Schengen Information System with Brexit and was relegated to third-party status within EUROPOL. Therefore, both actors could find a mutually beneficial agreement to grant the UK greater access to EU information systems in exchange for UK participation in this new intelligence cooperation service. 

Joint procurement and joint production: The UK's armament supply for Ukraine severely depleted its stockpiles and occupied its production lines. This disruption affects an industry remarkably integrated with the rest of Europe. It is at risk of “going down” in time, as with other recent EU collaboration projects on industrial defence synonymous with UK exclusion. EU projects have included the Permanent Structured Cooperation, which is understood as a forum for European defence firms to discuss and implement new cooperative projects. These can be open to external firms, including those from the United Kingdom and the United States. However, they require approval and fit the “political, substantive and legal conditions.” The UK has shown its openness to the idea by joining the PESCO  military mobility scheme. However, this project included the United States and Canada when the UK joined. This clearly shows some of the issues discussed above, notably the difficult relationship between EU defence and NATO and Brussels's potential lack of will to develop a solid bilateral relationship. However, PESCO remains a very open structure in which third countries are generally welcome and where serious defence capability development can be undertaken. 

Strategic cooperation: Rapid improvements can happen when there is greater coordination between the EU and the UK concerning the Middle East, Ukraine, and the Indo-Pacific. A new security pact could help formalise discussions and incite leaders to meet regularly and not as a response to an ongoing crisis. Such efforts have started taking place to a limited extent, but these still need to be expanded compared to the potential gains at stake. After the council meeting David Lammy attended, he hinted at further coordination regarding sanctions on Russia and help to Ukraine. While his monthly presence is not permitted (he received an invitation from Josep Borell), creating other structures allowing mutual help and joint action is mutually beneficial. It would not require compromise on UK sovereignty or EU principles. 

About the Author 

Alexandre Doré, Programme Analyst - Europe 

Alexandre Doré joined London Politica's Europe Desk in 2024. He is currently pursuing a master's degree in European and International Politics and Policy at the LSE. He holds a first-class bachelor’s degree in International Relations from King’s College London. Alexandre has previous experience in policy-making in France and for various non-governmental organisations. He specialises in the European Union, particularly in EU foreign policy or defence matters. His work on European defence has previously been published in the Future Europe Journal.