Resetting (modestly): The UK-EU Security and Defence Partnership

This analysis was first published by Britain's World: Council on Geostrategy.

The summit between the United Kingdom (UK) and the European Union (EU), held on 19th May 2025 at Lancaster House, yielded a Security and Defence Partnership which, while notable for its timing and symbolism, falls short of what is strategically necessary. The agreement codifies existing cooperation without offering a blueprint for the structural and strategic alignment required in today’s deteriorating security landscape. In its current form, the partnership signals a willingness to stabilise relations, but misses a critical opportunity for a partnership which would contribute to shaping the future of European security architecture.

The UK and EU have both faced pressure to redefine their foreign and security cooperation following the re-election of Donald Trump as President of the United States (US) and Russia’s full-scale invasion of Ukraine. Yet, five years post-Brexit, their shared response to these challenges remains informal and piecemeal outside of their cooperation on support for Ukraine. The long-anticipated Security and Defence Partnership unveiled on 19th May promised a shift to structured cooperation. However, its contents suggest a cautious political manoeuvre rather than a transformative moment in UK-EU relations.

A new UK-EU Security and Defence Partnership

Compared to the aspirations set by the current UK government in advance of coming to power – which envisaged a wide-ranging ‘security pact’ – or measured against existing EU security and defence agreements with third countries, this partnership cannot be considered an ambitious agreement. It was presented as a central component of a broader UK-EU Strategic Partnership presented at the summit, yet a closer examination reveals that it does not exceed the models which the EU already has in place with other partners.

At its core, the Security and Defence Partnership is essentially a commitment to regular dialogue and exploratory cooperation.

The agreement’s preamble stresses the two sides’ shared interests and alignment on Europe’s security order in the face of Russian aggression. However, while it establishes new forums for consultation, it largely formalises dialogue which could have been initiated much earlier, particularly after the inauguration of President Trump last autumn when closer coordination became more urgent.

Structured consultations: Formalising dialogue rather than delivering strategy

At its core, the Security and Defence Partnership is essentially a commitment to regular dialogue and exploratory cooperation. The framework sets up a series of consultation mechanisms intended to facilitate strategic exchange and oversight of cooperation. These include six-monthly high-level meetings between the EU High Representative for Foreign Affairs and Security Policy and the UK Foreign and Defence Secretaries for strategic consultations on priority regions and threats (e.g., Ukraine, the Indo-Pacific, the Western Balkans and hybrid threats). Britain will now be invited to high-level EU meetings (including, where appropriate, at the European Council) and, reciprocally, the EU High Representative will be invited to high-level UK meetings. These will be underpinned by arrangements for senior officials to coordinate activities. These arrangements have been absent since the UK-EU Trade and Cooperation Agreement (TCA) took effect in 2021, leaving a gap in formal foreign policy coordination. Their introduction now is welcome, but belated. In effect, the new partnership is putting a formal stamp on practices of consultation which could have arguably been activated in response to Europe’s deteriorating security environment much sooner.

Crucially, while the Partnership creates forums to talk, it does not itself guarantee deeper action. All substantive cooperation flowing from these dialogues will require separate agreements or case-by-case arrangements. The Partnership opens the door for Britain to plug into existing EU defence cooperation tools – from Common Security and Defence Policy (CSDP) missions to Permanent Structured Cooperation (PESCO) projects – but breaks no new ground; it mirrors arrangements which the EU already has with other partners and leaves the heavy lifting for follow-on agreements. For example, the text signals that the UK may align with existing EU third-country frameworks – such as contributing to CSDP missions via a Framework Participation Agreement, or signing an Administrative Arrangement with the European Defence Agency (EDA) – but it commits neither side to specific outcomes. These possibilities remain subject to further negotiation and, in some cases, political hurdles. The agreement cautiously references building momentum for British participation in PESCO projects, specifically the Military Mobility project, although this has been stalled due to objections by the Government of Spain over an unsettled dispute regarding Gibraltar’s relationship with the EU.

A broad, but conventional, agenda for cooperation

The bulk of the agreement is devoted to enumerating areas of cooperation – essentially a laundry list of security topics where Britain and the EU pledge to consult and coordinate. These range from traditional and well-trodden domains to newer security challenges. For example, the Partnership calls for exchanges on regional security issues of common interest (with an immediate focus on supporting Ukraine, as well as regions such as Eastern Europe, the Western Balkans, the Indo-Pacific and Africa). Thematic cooperation is outlined across cyber security, space security, hybrid threats, critical infrastructure resilience, counter-terrorism, countering foreign information manipulation and interference (disinformation), non-proliferation and arms control, security capacity-building for partner countries, and joint training and education in defence.

This comprehensive agenda is sensible; it covers virtually the entire spectrum of contemporary security concerns. Indeed, cooperation on many of these issues is already pragmatically underway through informal channels or wider groupings – for instance, UK-EU coordination on sanctions and military aid for Ukraine via the Group of Seven (G7), the North Atlantic Treaty Organisation (NATO) and ad hoc formats. The new Partnership simply codifies these as areas for structured dialogue, and aims to boost cooperation in each field – but it does not itself provide new resources, joint programmes or decision making mechanisms to tackle these issues. In terms of tangible output, it commits to information exchanges, coordinated assessments and the possibility of mutual participation in each other’s initiatives (for example, Britain may join EU cyber capacity-building efforts for third countries, or the EU may take part in UK-led defence training programmes). These are constructive steps to knit together UK-EU cooperation, but they remain incremental.

In sum, the cooperation agenda is broad but thin: it identifies all the right topics and commits to dialogue, but any operational depth will have to develop over time, on a case-by-case basis.

Missing pieces: Industrial cooperation and the SAFE initiative

One striking omission in the Security and Defence Partnership text is any substantive provision for Britain in the EU’s evolving defence industrial strategy. The only nod in this direction comes outside the main agreement, in a separately agreed UK-EU Common Understanding on a ‘Renewed Agenda’ for cooperation. There, both parties ‘should swiftly explore any possibilities for mutually beneficial enhanced cooperation created by the SAFE instrument once adopted, in accordance with their respective legal frameworks’.

This is uncharted territory, and political hurdles abound. Within the EU, there is not unanimous enthusiasm for opening SAFE to the UK.

This rather convoluted formulation refers to the EU’s proposed Security Action for Europe (SAFE) initiative: a major financing vehicle to bolster Europe’s defence industrial base and fund urgent military procurements. SAFE is part of the EU’s broader post-Ukraine conflict rearmament effort (ReArm Europe), and would allow EU member states joint access to up to €150 billion (£126 billion) in EU-backed loans for critical defence projects. The new Security and Defence Partnership is only the first step towards possible British involvement in European defence programmes. Ursula von der Leyen, President of the European Commission, cautioned that a ‘second step’ will be required before UK industry can actually become eligible to compete for contracts under SAFE.

The implications of this pending SAFE deal are potentially significant. British defence industry bodies have therefore greeted the prospect with cautious optimism. However, this looks set to be a pay-to-play model, akin to other EU policy areas where non-EU countries gain admission to EU programmes, and where the UK has already accepted the principle as the price of its inclusion in the EU’s Horizon research and innovation programme. The scale of contribution, the legal parameters and any conditions on British participation remain to be settled. This is uncharted territory, and political hurdles abound. Within the EU, there is not unanimous enthusiasm for opening SAFE to the UK. France, in particular, has voiced concerns – and Paris is wary that admitting British defence firms could undercut French industry or skew the benefits of EU funding away from domestic champions. Such concerns reflect a broader debate in Brussels about how much to cooperate with external allies on defence procurement.

Overcoming these reservations may require careful compromises, such as limits on certain sensitive projects or guarantees that European (EU-based) industries remain the primary beneficiaries. Additionally, any UK association to EU defence programmes will likely oblige British entities to adhere to EU rules on technology transfer, security of supply and export controls – a sticking point which has in the past hampered cooperation and participation. As well as this, it must also navigate UK domestic politics.

Conclusion: A step forwards, but no game changer

Ultimately, the new Security and Defence Partnership is best seen as formalising the status quo and creating a framework for further cooperation, rather than a transformative leap in UK-EU relations. This is certainly a positive development in terms of mending ties – after years of estrangement post-Brexit, Britain and the EU will now have regular channels to discuss security policy at all levels. However, it does not represent a strategic shift in itself; there is little in the agreement which fundamentally changes either party’s commitments or capabilities.

To respond truly to Europe’s moment of strategic reckoning, both sides must go beyond the tepid cooperation provided for in the Agreement. A renewed effort is needed to incorporate the UK into the EU’s defence industrial strategy, operational planning and security policy making. Anything less risks institutionalising irrelevance into UK-EU relations at a time of existential strategic flux.