A landmark Defence and Security Pact between the EU and the UK is signed and with it a new chapter in post-Brexit relations begins.
As the dust settles on the symbolism, a more difficult conversation begins on how to turn diplomatic momentum into meaningful, accountable, and future-proof cooperation. What could a EU-UK defence pact deliver, and what should it avoid?
Public support is there, but so are the risks
Public and political momentum is tangible, but governance still lags behind. Support for closer defence ties is already mainstream on both sides of the Channel. Yet the oversight, safeguards, and transparency we apply in other sectors (like humanitarian aid) remain worryingly absent from discussions about European defence.
Over 60% of UK citizens support closer defence ties with the EU, a striking shift from past scepticism around joint military ventures. This opens a window for cooperation rooted in shared threat perceptions, particularly vis-à-vis Russia and US foreign policy. This newfound openness cannot be taken for granted. Unlike other policy areas (e.g. migration or trade), defence cooperation seems less politically “sticky”, but will remain so only if its outcomes are seen as credible, effective, and fair.
Industrial integration is not neutral
The potential for joint procurement and industrial collaboration is immense, but not without significant governance and sovereignty risks. The UK’s defence industry is deeply integrated with the US, raising concerns about how “European” future joint systems with the UK would be. British defence giants like BAE Systems and Rolls-Royce operate extensively within the US market, and their products often include US-origin components.
This matters because such components can carry legal and political restrictions on their use, such as the Arms International Traffic in Arms Regulations (AITA), which can restrict the export or operational use of any system containing components of American origin. In Ukraine, for example, these constraints have already had real consequences: certain Western-made systems cannot be used for long-range strikes or exported without prior authorisation. In this way, third countries may still retain veto power over how weapons are deployed, even in urgent wartime scenarios.
The EU-UK Defence Pact aims to deliver strategic flexibility and autonomy. For this to materialsie, any co-produced systems must be designed from the outset to be free from those restrictions. Otherwise, European states risk being politically aligned but operationally constrained.
Democratic oversight remains fragmented
European defence is still more ambition than architecture. While the EU has taken major steps toward greater coordination, defence remains a patchwork of national systems, divergent priorities, and fragmented oversight. The EU cannot currently fund military operations from its core budget, and procurement remains largely a national prerogative. Crucially, as defence budgets rise, governance gaps widen. NATO, the EU Parliament, and national parliaments exercise some oversight, but EU-level defence cooperation lacks a robust, integrated, and harmonised accountability framework.
Parliamentary scrutiny varies widely and even in member states with relatively strong national controls (e.g. Germany, where parliament must approve contracts over €25 million) there is limited political appetite to elevate or align oversight at the EU level. The EU can support coordination and financing, but lacks meaningful levers to enforce transparency or ethical standards across borders. The risk is that joint initiatives, procurement programmes, and industrial integration will advance faster than the institutions designed to govern them.
Strategic urgency Is driving speed, but scrutiny is lagging
The risk remains that political capital is spent on symbolic breakthroughs rather than institutional substance. Momentum should not override scrutiny. The summit may have delivered a strong political gesture, but all the critical legal and practical details—on access, conditionality, and governance—will only be hashed out in the months ahead. And behind the political consensus lie unresolved questions: under what conditions will UK firms access EU defence funds (e.g., the new €150bn SAFE facility)? How will rules of origin be defined for joint procurement? Can export control regimes be aligned to prevent governance loopholes? The current moment might be a “market-moving opportunity” for defence actors, but the investment case remains underspecified.
Also, speed must not come at the cost of integrity. Joint declarations are welcome, but mechanisms must follow. Political incentives may prioritise quick wins, especially in the face of domestic pressures. Meanwhile, divergent French and German views on UK involvement, and rising populist sentiment across Europe, may push governments toward optics rather than institutional depth.
Defence without accountability is a false promise
The takeaway was clear: cooperation must be conditional on transparency. With the pact now agreed, attention must turn to how it will be implemented. For this new phase of EU–UK defence cooperation to succeed, its delivery must match its ambition with transparency and accountability built in from the start.
At TI-DS, we believe that how defence cooperation is built matters just as much as what is built. The UK and EU have a shared interest in security. They must now demonstrate a shared commitment to governance. With new money, new mechanisms, and new threats, the time to embed transparency and integrity is now not after the contracts are signed.
Dr. Francesca Grandi, Head of Programme, Transparency International Defence and Security