The UK–EU Security Pact: A Necessary Reset, but Not Yet the Scale Europe Needs
Mike Buckley and Dr. Ben Martill
The Security and Defence Partnership agreed at the May UK–EU Summit represented an important step forward after several years in which political mistrust and post-Brexit tensions stalled cooperation. At a moment of profound geopolitical volatility—marked by Russian advances in Ukraine, a more transactional US posture, and increasingly sharp transatlantic divergences—the pact provided a welcome re-institutionalisation of dialogue and a necessary platform for rebuilding habits of cooperation. It codified what had developed informally since 2022 and reopened channels that were allowed to atrophy, creating predictability in an area where uncertainty is itself a strategic risk.
The pact’s value lies first in the establishment of structured political and working-level engagement. Regular ministerial dialogues will now take place, the UK will be invited to EU Foreign Affairs Council meetings where appropriate, and officials will work to identify further areas of cooperation in specific areas. UK participation in EU defence initiatives is also mooted, although the terms on which this would take place are the subject of disagreement.
After several years in which the UK operated outside the EU’s security structures, these frameworks have immediate practical benefits: they reduce the risk of misunderstandings, enable smoother operational cooperation, and provide the expectation cooperation will continue into the future. The agreement gives officials a basis to coordinate policy rather than rely on ad hoc contact as well as a platform for further engagement in the future.
Yet the pact also reflects the constraints of the moment in which it was negotiated. It was conceived primarily to remedy the absence of any security pillar in the 2020 Trade and Cooperation Agreement rather than to address the far more severe strategic challenges facing Europe today. Much of what has been mentioned in the agreement was already happening informally. And crucial gaps remain—particularly the absence of provisions for UK participation in major EU defence-industrial initiatives, including the European Defence Fund and the new €150 billion SAFE programme, both of which will shape the continent’s defence-industrial base for decades.
This limitation has become even more apparent in recent days as UK–EU talks on SAFE have stalled. The Commission has reduced its financial ask substantially, yet London and Brussels remain far apart on a mutually acceptable contribution. This deadlock carries consequences. Without a settlement, the UK risks exclusion from one of the central instruments of Europe’s rearmament effort, and the EU risks weakening the industrial coherence it is seeking to build. In the context of a more isolationist US posture—illustrated starkly by Washington’s recent pressure on Kyiv to accept a US-Russian peace plan that would require major territorial concessions—the case for maximising European capability is stronger than ever. The question now is whether both sides can show the urgency necessary to reach an agreement.
Beyond these immediate issues, the broader strategic context demands a more ambitious approach. Europe faces a convergence of challenges unlike any in the post-Cold War period: an emboldened Russia with increasing battlefield momentum; a United States whose reliability can no longer be assumed; and a European defence landscape in which the scale of required capability development vastly exceeds the pace of current institutional arrangements. In this environment, the UK–EU pact is necessary but not sufficient. For Europe to defend Ukraine and deter Russia, UK–EU cooperation must shift from goodwill to urgent, deliberate action. This means moving beyond political symbolism to the hard practical questions of industrial capacity, joint procurement, standards alignment and sustained support for Ukraine’s long-term defence.
Recent UK bilateral agreements with France and Germany demonstrate that deeper cooperation is both politically possible and strategically beneficial. The Northwood Declaration has expanded Anglo-French collaboration across domains—cyber, space, nuclear deterrence and long-range strike—while the Kensington Treaty with Germany sets out the most significant UK–German defence framework in decades, covering mutual assistance, joint weapons development and industrial integration. The challenge now is ensuring that such initiatives complement rather than substitute for EU-wide coherence. A patchwork of bilateral deals cannot meet the scale of Europe’s security challenge. A continental strategy requires continental instruments.
For this reason, the next phase of UK–EU cooperation should focus on embedding the UK more structurally in Europe’s defence-industrial and capability-planning ecosystem. This does not require replicating membership, nor does it imply abandoning legitimate UK red lines. But it does require both sides to acknowledge that the strategic environment has changed, and that the costs of limited cooperation now outweigh the political sensitivities that previously constrained ambition. For the EU, that means moving beyond reflexive concerns about “cherry-picking” in areas where security imperatives differ from other domains. For the UK, it means recognising that Atlanticism alone is no longer sufficient to guarantee national or European security.
The Security and Defence Partnership is therefore best understood as a foundation rather than a finished product. It signals intent, re-establishes predictability, and enables cooperation that would otherwise be impossible. But neither Europe’s defence industrial base nor its strategic posture can be rebuilt on statements of intent alone. The task now is to convert today’s political goodwill into the concrete capability outcomes that Europe urgently needs: large-scale munitions production, integrated air and missile defence, shared ISR infrastructure, interoperable equipment, and the industrial partnerships necessary for sustained support to Ukraine.
The window for action is short. European leaders increasingly warn that further Russian aggression could be actioned within the next four years. If the UK–EU pact is to play a meaningful role in meeting this challenge, it must evolve quickly. Deepening the partnership is not a matter of political aspiration but of strategic necessity. Both sides should approach the coming months with urgency, realism and a shared understanding that Europe’s security will depend on the choices made now.
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