What should Britain’s future relationship with the European Union look like?
The Big Ask | No. 06.2025
Sir Keir Starmer, Prime Minister, travelled to Brussels on Monday to meet with the leaders of the 27 European Union (EU) countries at an informal meeting of the European Council, the first time a British prime minister has done so since Brexit. His Majesty’s (HM) Government has signalled its willingness for a ‘reset’ with the EU, but so far there has been more talk than action. So, in this week’s Big Ask, we asked eight experts: What should Britain’s future relationship with the EU look like?
Deputy director, Centre for European Reform
Sir Keir says that the UK is not ‘choosing between the United States (US) and the EU’, but the threats by Donald Trump, President of the US, to use tariffs and military might against friendly countries shows the risks of being too dependent on America. Sir Keir should build the closest possible relationship with the EU, in trade and security. Tariffs permitting, the US is likely to remain a major trade partner of the UK, and the bilateral defence and security relationship would be hard to replace in the short to medium term. But the EU is a significantly more important trading partner for Britain than the US is, and a government that prioritises growth would do well to seek to rejoin the single market – a step which would benefit Britain’s important services sector as well as its manufacturers.
The UK should also build on the discussions between Sir Keir and his EU colleagues this week and seek closer British involvement in European defence cooperation – even if this is currently a very poor substitute for what the US can bring to the table. Trump is an unreliable ally, as his attempts to pressurise Denmark into ceding Greenland show. And America’s military strength will not help the UK in a European crisis if US forces have been redeployed to confront the People’s Republic of China (PRC) – as some senior Pentagon officials reportedly want.
Researcher, Centre for Security, Diplomacy and Strategy, Free University of Brussels
When Sir Keir joined the EU’s 27 national leaders and Mark Rutte, Secretary General of the North Atlantic Treaty Organisation (NATO), in Brussels on Monday, he called for ‘an ambitious UK-EU security partnership’. HM Government’s reengagement with Europe on defence has already been marked by the signing of the Trinity House Agreement with Germany and a commitment to reboot of the Lancaster House Treaty with France, and more steps to strengthen ties with European allies are expected in the months to come.
At a time when large-scale conventional war rages on the European continent and Washington’s future commitment to European security is in doubt, close defence cooperation between Britain and EU countries is desperately needed. Such cooperation – whether in bilateral, minilateral, NATO or UK-EU formats – should focus on ensuring that rising defence budgets are spent efficiently to fill Europe’s most critical capability gaps and strengthen its war-fighting ability.
Reinforcing Europe’s patchy air and missile defence architecture and capacity for long-range strike are two priority areas, with ongoing initiatives such as Britain’s Diamond project or the European long-range strike programme named ELSA being helpful but not sufficient. New agreements on defence-industrial cooperation between Britain and EU countries are necessary too, even if complicated by rules on third country participation in various EU defence mechanisms.
The to-do list is long and none of its tasks are easy to tick off. But across Europe’s capitals, the motivation to succeed should be high: after all, it’s European security which is at stake.
Founder, Centre for Britain and Europe and Director, International Training Centre for Authorities and Leaders, University of Surrey
Britain is at last resetting its relationship with the EU. As always, the desire to push for ‘high politics’ and land big wins is a real temptation. The stakes are certainly high enough: continued UK leadership, coordination and cooperation with its European allies and the EU itself over Ukraine remains key. This however, raises the option of enhanced British involvement in EU security operations and the emerging defence ecosystem more broadly.
The UK could usefully build on long-standing and recent bilateral defence deals with major EU countries through a series of operationally specific, but materially progressive commitments with the EU from which both sides would reap the benefits of interoperability and improved relations with industry. But trade is an equally hot topic. The two most fruitful avenues here include a far more ambitious goods and services deal worked into the present UK-EU Trade and Cooperation Agreement – due for renegotiation next week – and looking seriously at the EU’s proposal that the UK join the 25-strong Pan-Euro-Mediterranean convention launched in 2012, which allows members to trade with each other through common rules. Pushing ahead on both would gradually, but clearly deepen Britain’s alignment with its largest trading partner, boosting the EU’s ability to conduct an enhanced trade war – if it comes to that – with the US.
Dr Timothy Less
Convenor, Geopolitical Risk Study Group, Centre for Geopolitics, University of Cambridge
The UK’s relationship with the EU should be defined by its strategic interest in maximising its security and prosperity in an era of deepening geopolitical competition and rising tensions between the EU and the US, manifest in recent clashes over Greenland and an incipient trade war.
There’s a case that, in these increasingly turbulent times, Britain should bandwagon with the EU, its geographical neighbour and main trading partner. That could mean integration, potentially up to joining the EU’s customs union or even the EU itself, which polls suggest a majority of British voters would support.
However, doing so would come at a price. The EU’s interests are not the same as the UK’s and the EU is increasingly troubled, with stagnant economic growth and a politics marked by deepening tension and instability. Bandwagoning with the EU could also deny the UK the benefits of closer relations with the US and expose it to costs, such as trade tariffs.
Instead, Britain would be better off balancing between the two, extracting the benefits of constructive relations with the EU in areas such as trade and security, while resisting the EU’s efforts to pull the UK into its political, legal and regulatory ambit, or worse still, forcing it to adopt a position on a contentious topic such as trade or taxation which actively annoy Washington.
Additionally, the UK could extract the benefits of staying close to the US, its foremost political ally and ultimate security guarantor and whose economy is strong. Ideally, the US would like to draw Britain into its immediate sphere of influence, but it can live with a UK which is more detached if this means, for example, the British playing a large role in securing Europe.
Formally, Britain’s independence from the EU provides the opportunity for the UK to play this balancing role. The challenge, as always, will be to achieve this.
Co-founder and Director of Research, Council on Geostrategy
Britain’s relationship with the EU should be underpinned by its fundamental interests, the most important of which are to retain democratic sovereignty, prevent a hostile competitor from emerging from across the English Channel, and boost technological innovation and economic prosperity.
Tempting as it might be, the UK should not seek closer relations with the EU if the British economy is bound into the EU’s regulatory orbit. The EU economy is in relative economic decline as economies in North America and the Indo-Pacific surge. If the UK can gain greater access to the EU market without jeopardising its long-term connections to other parts of the world, it should do so. But not at the expense of them.
Ditto, Britain has a powerful bargaining hand: it is a nuclear weapons state with a deep and pervasive interest in continental security. Many EU countries now face mounting threats – not least from Russia – which strengthens the UK’s hand as a security provider. HM Government has failed to deploy this card properly yet; it should do so more shamelessly and vigorously.
What the UK does need to do is to use its geopolitical weight to prevent EU defence structures from emerging over which it has no control. This does not mean it should join them as some peripheral party; rather, it means HM Government should seize the initiative either in providing alternative ideas or restructuring them so that the UK has an equal say in how they are run and develop.
25 years ago, Sir Robert Cooper warned that without strong defences, the EU would be enveloped by the ‘law of the jungle’. Today, Europe itself is afflicted by geopolitical struggle. The EU needs to come to terms with the fact that, without the UK, the ‘jungle’ will only thicken.
Former British diplomat, writer and podcaster and Associate Fellow, Royal United Services Institute
For those of us that regret Britain’s departure from the EU, it’s tempting to respond with a simplistic call for the UK to rejoin. But, however enticing in the long-term, my starting point would be that the urgent challenges which need to be addressed by Britain are no different to those faced by the EU. The economies of both the UK and EU nations are insufficiently dynamic, an issue compounded by ageing societies which require increasing spending on care. This contributes to a political culture that is giving up on mainstream parties and turning to extremes. Existential challenges of insecurity – the climate crisis and resulting migration, the declining reliability of the US as an ally and Russia’s ever-increasing belligerence feed those extremes.
Once we recognise the shared threats, those can define the future relationship. We should accept and embrace the fact that all responses require the closest UK-EU coordination across economic, security and political pillars. Accepting that as the starting point, rather than fantasies of ‘global’ Britain, is key. Institutionally, this will create a natural pathway to increasing alignment as UK-EU joint working becomes the default option. Focusing on shared interests rather than institutional structures will move the relationship onto more fertile ground.
Research Fellow, German Marshall Fund
The dynamic between London and Brussels has significantly changed over the last year: with a new British government, a new EU Commission, and massive security challenges for Europe ahead, both sides are clearly working on enhancing their ties.
This ‘reset’ was overdue, and now is a window of opportunity to get the relationship right. In light of Russia’s war against Ukraine and the uncertain trajectory of European security, cooperation on security and defence should be the absolute priority – potentially even through a security pact ahead of a more comprehensive UK-EU agreement, where many areas still remain to be clarified.
With the looming threat of tariffs from the US, the UK and EU would be well advised to double down on cooperation on competitiveness and economic security as well, including through creating European champions in critical areas. And while there might be – for good reason – an urge to prioritise ‘high politics’, namely security and economics, in the short-term, the EU and the UK must get cooperation on research, science cooperation, and youth mobility right, which will be the base for long-term cooperation on future challenges.
What the relationship needs most in all of this, and especially after the Brexit tensions, is pragmatism: both sides should avoid issue-linkage and tit-for-tat across policy areas – in light of the challenges Britain and the EU are facing, energy on both sides should be better invested than in political games.
Professor of International Relations, University of Kent
The discussion on Britain’s future relationship with the EU is currently overwhelmingly focused on the means by which an improved relationship might be demonstrated. This is to the detriment of a full consideration of the ends to which the relationship might serve for both parties.
The current relationship demonstrates all the conditions of détente – both parties have found ways to cooperate, which privilege achieving a better working relationship while setting aside significant differences on the basis on which their respective economies and politics are orientated. Unless the UK rejoins the EU, or the EU dissolves, or significantly alters its vocation as a political and economic integration project, each will retain distinctive standpoints from which they derive their perspective on their relationship.
This is not to say that important and useful UK-EU agreements might not be made which reduce the friction in their trading relationship or allow for closer cooperation on issues of shared interest where there is a common outlook. A shared language of public diplomacy that stresses a ‘reset’ is entirely appropriate for reaching understandings and agreements on issues which relate to technicalities of the relationship.
However, what is more necessary is a recasting rather than a resetting of relations. The shared challenges of European security, a more transactional transatlantic partnership and in an era in which international order is in flux, require a much more fundamental new form for the relationship.
Relations between EU countries and institutions, the UK and other non-EU European states need to be pursued as an alliance relationship – and an alliance for the purpose of mutual security. This is not to supplant NATO, but to recast the relationship as one predicated on how it provides for mutual security across the full gamut of shared security challenges. That would be a security pact worth pursuing.
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