Can the United Kingdom join the European Defence Fund?

Wednesday 4 February 2026

The question of whether the United Kingdom should join the European Defence Fund has moved from the margins of post-Brexit debate into the centre of strategic discussion in Whitehall, Brussels and European capitals more broadly. It is a question shaped not only by institutional politics, but by the hard realities of war on the European continent, the evolving nature of defence technology, and the United Kingdom’s own uncertain place within the European security architecture after her departure from the European Union.

The European Defence Fund, established to support collaborative research and development in defence technologies and capabilities, represents a deliberate effort by the European Union to reduce fragmentation in European defence markets and to strengthen collective military capacity. It is explicitly designed to encourage cross-border industrial cooperation, to reduce duplication of effort and to ensure that European armed forces can draw upon a coherent and competitive industrial base. In doing so, it challenges long-standing national reflexes in defence procurement, including those that have traditionally characterised British policy.

For the United Kingdom, the issue is immediately political. Joining the European Defence Fund would require a form of structured participation in an EU programme that goes beyond ad hoc cooperation. For some, this risks being portrayed domestically as a partial reversal of Brexit, or as a concession of sovereignty in an area long regarded as a core attribute of the state. Defence, perhaps more than any other policy domain, remains symbolically linked to national independence. Any suggestion that British defence planning or industrial priorities might be influenced by Brussels inevitably attracts suspicion in parts of the British political class and press.

Yet this sovereignty-based objection sits uneasily with strategic reality. The United Kingdom has never pursued defence in isolation. She remains deeply embedded in NATO structures, relies heavily upon interoperable systems developed in cooperation with allies, and has long accepted constraints arising from alliance membership. Participation in NATO has never been framed as a loss of sovereignty, but rather as its practical reinforcement. The question, therefore, is whether participation in the European Defence Fund represents a fundamentally different type of constraint, or merely another layer of structured cooperation adapted to contemporary threats.

From an industrial perspective, the stakes are substantial. British defence companies have historically been major players in European collaborative programmes, from aircraft to missiles and naval systems. Exclusion from the European Defence Fund risks placing them at a structural disadvantage relative to EU-based competitors, particularly in research-intensive fields such as unmanned systems, artificial intelligence-enabled command structures and next-generation sensors. Over time, this could lead to the gradual marginalisation of British firms within European supply chains, with consequences not only for exports but for domestic military capability and skilled employment.

Conversely, joining the Fund would require acceptance of its rules, including provisions on intellectual property, export controls and eligibility. These rules are designed to ensure that EU funding benefits EU strategic autonomy. For the United Kingdom there is concern that participation might restrict her freedom to export defence equipment to non-European partners, or to integrate European-funded technologies into programmes involving the United States. Given the depth of the UK–US defence relationship, this is not a trivial concern. Any arrangement would need careful calibration to avoid placing British industry in a position of divided loyalty between regulatory regimes.

There is also a strategic signalling dimension. Were the United Kingdom to join the European Defence Fund, she would be making a statement about her long-term commitment to European defence beyond NATO alone. This could strengthen political trust with European partners who, since Brexit, have sometimes questioned Britain’s willingness to invest institutionally in Europe’s security rather than merely to act as an external guarantor. At a time when the United States’ strategic focus is increasingly divided between Europe and the Indo-Pacific, European states are acutely aware of the need for greater internal coherence. British participation could enhance that coherence, particularly given her military weight and operational experience.

At the same time, there is a risk that joining the Fund could blur institutional boundaries between the European Union and NATO. Some central and eastern European states remain wary of EU defence initiatives that might duplicate or dilute NATO’s primacy. The United Kingdom has historically shared these concerns and has often acted as a transatlantic bridge within European security debates. Participation in the European Defence Fund would need to be framed explicitly as complementary to NATO, rather than as an alternative to it, if it is not to unsettle alliance dynamics.

Finally, there is the broader question of strategic culture. The European Defence Fund is not merely a financial instrument. It is part of a wider effort to encourage European states to think collectively about capability development and long-term military planning. The United Kingdom, with her strong traditions of national strategic assessment and expeditionary thinking, may find aspects of this culture both constraining and frustrating. Yet she may also find that absence leaves her reacting to decisions shaped without her input, rather than influencing them from within.

In weighing these issues, the choice facing the United Kingdom is less stark than it may appear. The decision is not between sovereignty and subordination, but between structured engagement and strategic detachment. Joining the European Defence Fund would involve compromise and political risk, but remaining outside carries its own long-term costs, both industrial and strategic. In a Europe defined increasingly by insecurity and technological competition, the question is not whether cooperation entails constraints, but whether those constraints are outweighed by the ability to shape outcomes in a system that will, with or without Britain, continue to evolve.