The UK–EU summit will bring some progress on defence cooperation. But more could be done on aid and trade

The summit will be valuable if it yields a substantive defence agreement. But wider foreign policy issues should be part of the agenda.

Expert comment Published 14 May 2025 Updated 16 May 2025 4 minute READ

Olivia O’Sullivan

Director, UK in the World Programme

On 19 May, UK and EU leaders will hold a summit focused on resetting post-Brexit relations, covering cooperation on issues including trade, and critically, security and foreign policy. 

One of the summit’s most likely outcomes is a new defence and security pact, an ambition the UK’s Labour party set out in its electoral manifesto last year. The UK and EU have pursued security cooperation in recent years, particularly over Ukraine. But a new pact would mark a meaningful step forward after years of minimal structured foreign policy and security engagement since the UK left the bloc. 

For the summit to lead to meaningful progress, any pact should lay the groundwork for deeper cooperation on defence funding, defence-industrial planning and longer-term geopolitical strategy. Without doing so it risks avoiding the central challenge: how both the UK and EU can defend themselves better in a less American world. 

There are promising signs the summit might deliver on these issues – but there are bigger questions too. 

While stronger defence cooperation is necessary, a more difficult and longer-term question is whether the UK and EU work can together on broader foreign policy goals at a time when US leadership is shifting, and multilateral institutions are under strain.

Defence and security cooperation must go further 

There is a strong case for a formal security and defence agreement. Under the current Brexit deal – the Trade and Cooperation Agreement – UK–EU engagement on defence and foreign policy is limited to some regular dialogues. That falls short of even earlier post-Brexit proposals, which envisaged a more structured diplomatic and defence partnership. 

More importantly, current arrangements don’t reflect today’s security environment. The UK and EU share strategic interests: in supporting Ukraine, managing the threat from Russia – and adapting to a world in which relying on long-term US military support is no longer a viable strategy.

The goal should be that future defence spending adds up to more than the sum of its parts…that requires joint planning, not just parallel efforts to increase national spending.

Politically, such a pact is achievable. Public opinion surveys in the UK and European countries suggest closer security cooperation is popular, and the practical benefits are clear. Ad hoc coordination already happens, but a more formal pact would support long-term planning and help the UK and EU align their defence investments and strategic thinking.

But any summit agreement needs to go beyond broad commitments to meet more frequently and undertake some joint security projects. Both the EU and UK face similar challenges: funding capability gaps, coordinating procurement, and reducing duplication across national defence industries. 

Fragmentation in European defence is a long-standing challenge. National decisions are often made in isolation, reducing efficiency and limiting the interoperability of countries’ armed forces. The goal should be that future defence spending adds up to more than the sum of its parts – and that Europe has the means to replace some US capabilities if needed. That requires joint planning, not just parallel efforts to increase national spending.

Ideally the pact would enable the UK to access emerging EU defence initiatives, particularly around joint procurement, industrial cooperation, and funding. The EU is not the main framework for defence cooperation in Europe – that remains NATO, alongside bilateral and smaller groupings – and other proposals exist for joint European defence spending. But the EU is becoming more important in shaping how European countries fund, develop, and coordinate defence capabilities.

The bloc’s proposed €150 billion loan facility and other initiatives under the ‘ReArm Europe’ plan are designed to help member states replenish and modernize their armed forces. A security and defence partnership should enable UK companies to fully access this facility, as similar partnerships do for other countries. It would make sense to bring the UK in – to strengthen the programme and align it with wider European defence efforts.

Wider foreign policy coordination 

The summit is also a moment to consider wider questions about the UK and EU’s geopolitical relationship: to what degree is either side prepared to go beyond defence cooperation to coordinate on broader foreign policy? 

American leadership is becoming more uncertain and international institutions are under pressure. The UK remains deeply tied to the US in terms of intelligence, defence posture, and diplomatic coordination. But it cannot ignore the possibility that the US’s withdrawal from global governance will force decisions that will have long-term ramifications.

After cutting most of its foreign aid spending, the current US administration is reviewing its membership in several UN agencies and other international bodies. If it withdraws from these institutions or reduces funding, others may need to fill the gap. That would mean maintaining support for multilateral development banks, global health partnerships, and humanitarian agencies. 

These institutions are critical to supporting developing countries, but also to global stability and to managing future crises. Several are seeking new funding in 2025, and there is a growing mismatch between needs and available resources. 

European countries, including the UK, have also cut aid budgets in recent years. But they should consider working together to align what remains of their aid budgets, coordinate priorities, and reduce duplication. 

The UK’s recent trade pact with the US…does not necessarily foreclose deeper alignments with the EU – but in future choices between the two may be necessary. 

Similar questions exist on trade. The US may well continue with its use of tariffs and other economic pressures to extract policy concessions from allies and non-allies alike. 

Other countries will need to decide whether to pursue their own narrow exemptions from the US or try to uphold wider trade norms in response – potentially by working with similar trading nations in the Indo-Pacific. The UK’s recent trade pact with the US is not a substantial trade agreement and does not necessarily foreclose deeper alignments with the EU – but in future choices between the two may be necessary. 

The UK and EU countries are not perfectly aligned on all these issues. And political shifts on either side – not least towards the populist right – could complicate any ambitions to craft an enduring approach. Old concerns about trade and mobility between the UK and EU could also hamper wider cooperation. But there are some global issues on which the two consistently share interests, and where American leadership is becoming uncertain. 

This is where the summit could mark a shift, not just by announcing a security pact, but by beginning a broader conversation about how and where the EU and UK want to act together as global players. Will they seek to combine their strengths to jointly shape the international order? Or can they only respond to a changing world in which they have less influence?