Britain should explore what it calls a Deterrence Union with the European Union, formally extending its nuclear and conventional deterrent over the bloc in exchange for bespoke access to European defence funds, according to a report published by the Council on Geostrategy.
The paper, titled Towards a Hercules Hold: Maintaining a transatlantic defence industrial base, is written by Paul Mason and William Freer and carries a foreword by Tan Dhesi, the Labour MP for Slough and chair of the House of Commons Defence Committee.
Its central argument is that the transatlantic defence industrial base has begun to split, with Washington reprioritising resources towards hemispheric defence and countering China while the European Union deploys instruments such as the €150 billion SAFE facility in pursuit of strategic autonomy, and that those European mechanisms increasingly mandate the exclusion of third countries. Britain, sitting outside the European Union while maintaining deep security ties with Washington, is described as squeezed between two diverging defence giants and facing what the authors call a dangerous Hobson’s choice in capability standardisation.
The bridge has stopped working
The authors argue that the role Britain has traditionally assigned itself, acting as a transatlantic bridge, no longer serves the purpose it was designed for.
They write: “The historic approach of acting as a more passive transatlantic ‘bridge’ will prove insufficient to securing British interests. Instead, Britain should see itself as central to establishing a ‘Hercules hold’ to grip and sustain two diverging pillars. By focusing defence investment on select capabilities and championing interchangeability, HM Government can wield the influence necessary to maintain access to US technology while accelerating European rearmament.”
According to the report, further bifurcation risks cutting European allies off from cutting-edge American research and development along with North American surge capacity, leaving European nations with widening gaps in the high-end capabilities where the United States leads, among them ballistic missile defence, hypersonic strike and space systems, while integrated transatlantic defence firms face severe supply chain disruption.
What is being proposed
The Deterrence Union is the recommendation likely to attract most attention, since it would involve Britain formally offering nuclear protections to the European Union in return for deeper access to its defence market.
Alongside it the authors recommend championing hardware and munitions interchangeability across NATO, so that equipment can be physically swapped between allied platforms, and investing in a select portfolio of high-value technological chokepoints where British engineering becomes indispensable to both Washington and Brussels. They also call on the government formally to back the Canadian-led Defence, Security and Resilience Bank as a source of non-exclusionary funding for transatlantic projects.
Interchangeability is the same concept the First Sea Lord set out in an interview published last month, describing it as going beyond interoperability so that it becomes agnostic which nation is conducting a given task, with allied navies acting for each other’s collective requirements and able to exchange capabilities.
Why the timing matters
The report lands as the American review of force posture in Europe gets under way. Elbridge Colby, the Under Secretary of War for Policy, told a meeting in Brussels last week that the review would examine the strategic posture of American forces on the continent even as Washington prioritises the Western Hemisphere and the First Island Chain, and confirmed that allies had been sent a written questionnaire seeking their views.
British access to European defence funding instruments has been under negotiation since 2024, and the SAFE facility in particular has been the subject of argument over the terms on which non-member states can participate.
Dhesi, who wrote the foreword, pressed the Prime Minister at Prime Minister’s Questions on Wednesday to commit to a pathway to three per cent of gross domestic product on defence by 2030, telling the Commons that Britain faces a significantly increased threat level and a United States leadership for which European security is no longer a priority.
The Council on Geostrategy is a London-based think tank founded in 2021 which focuses on British foreign and defence policy, the Indo-Pacific, and the maritime and technological dimensions of national strategy. Paul Mason is a journalist and author who co-presents the organisation’s Defence Talks podcast.
Genuinely worrying about just how submarine crews the UK actually has. There are at least three crews (two SSBNs, one SSN), and I’m guessing probably two more on top of that, but beyond those five crews, IDK.