In a significant move for European security, the European Union and the United Kingdom have formalized a Security and Defence Partnership, marking the most comprehensive framework for UK-EU defense coordination since Brexit. This agreement, concluded at the first EU–UK Summit in London on May 19, 2025, comes at a pivotal moment as Europe faces mounting security challenges, including Russia’s ongoing aggression in Ukraine and broader geopolitical instability.
The partnership is designed to facilitate regular high-level dialogue, strategic consultations, and joint initiatives, with the possibility for the UK to participate in specific EU defense projects. It reflects a joint determination to reinforce European security in light of shifting global power dynamics and underscores the strategic importance both sides place on close, principled cooperation.
Context: A Response to Shared Threats
The agreement is rooted in the recognition that neither the UK nor the EU can afford to address complex, transnational threats alone. The security environment in Europe has become increasingly volatile, with Russian aggression, hybrid warfare, and global supply chain vulnerabilities posing significant risks.
EU High Representative for Foreign Affairs and Security Policy, Kaja Kallas, emphasized the shared responsibility:
“The agreement for a new EU-UK Partnership on Security and Defence shows our shared responsibility for security in Europe and beyond. With this we will keep our citizens safer in the years to come. We are determined to increase our cooperation in an increasingly dangerous and hostile global environment, be it in tackling cybersecurity and hybrid threats or increasing collaboration between our defence industries. The EU and UK clearly see eye-to-eye on so many levels. We both see Ukraine’s security as our security and have taken the same fundamental decisions to support the country against Russia’s aggression. Today our message is simple: we are both committed to working together for our collective security, because we are all stronger when we do.”
Key Pillars of the Partnership
Structured Dialogue and Joint Initiatives
The agreement establishes a framework for regular consultations between the UK Foreign and Defence Secretaries and their EU counterparts. A dedicated annual Security and Defence Dialogue will be held, complemented by working-level meetings and thematic exchanges on issues such as cyber threats, disinformation, arms control, and crisis management.
The UK will also be invited to participate in EU high-level defense events, while EU officials may attend UK-led meetings. This structured, forward-looking framework is intended to ensure that cooperation remains dynamic and relevant to emerging threats.
Comprehensive Areas of Cooperation
The partnership covers a broad spectrum of security and defense areas, including:
- Peacebuilding and crisis management under the Common Security and Defence Policy (CSDP)
- Maritime and space security
- Cybersecurity and emerging disruptive technologies
- Countering hybrid threats and enhancing critical infrastructure resilience
- Fighting foreign information manipulation and disinformation
- Counterterrorism and preventing violent extremism
- Addressing the climate-security nexus
- External aspects of economic security and irregular migration
Support for Ukraine and Strategic Regions
A significant emphasis is placed on joint support for Ukraine, with both the UK and EU having already trained over 120,000 Ukrainian troops through their respective missions. The partnership aims to maintain and expand this cooperation, while also exploring collaboration in other regions such as the Balkans, Indo-Pacific, and Sahel.
Defense Industry and Economic Cooperation
The agreement opens the door for UK companies to benefit from the EU’s proposed €150 billion defense procurement program, potentially boosting joint investment in the defense industrial base. European Commission President Ursula von der Leyen highlighted this aspect, stating,
“This is the first step towards U.K. participation in Europe’s defense investment program. This security and defense partnership opens the door towards the joint procurement.”
Tom Saunderson, a corporate partner at Browne Jacobson, noted,
“The announcement of security pact between the UK and the EU is not merely a reflection of the shifting dynamics in global defence partnerships, but it could also be seen a proactive step towards securing economic benefits for the UK’s defence sector.”
Maritime Security and Hybrid Threats
The partnership commits both sides to closer coordination at sea, including operations in contested waters like the Red Sea and joint efforts against sanctions-evading “shadow fleets”. There will also be regular exchanges on maritime security, with a focus on protecting subsea infrastructure and navigation routes.
On hybrid threats, the UK and EU will collaborate to counter foreign information manipulation, enhance infrastructure resilience, and improve crisis preparedness, particularly in the face of disinformation campaigns and hostile cyber activity.
Sovereignty and NATO Integration
Both parties have emphasized that the Security and Defence Partnership is a non-binding political framework that respects their respective sovereignty. The UK retains full control over its participation in EU initiatives, and the EU maintains its decision-making autonomy.
The partnership is explicitly designed to reinforce, not replace, the European contribution to NATO, which remains the cornerstone of Euro-Atlantic security. The agreement is seen as complementary to existing bilateral and multilateral security arrangements, ensuring that Europe’s collective defense is strengthened without undermining national prerogatives.
Implementation and Future Prospects
The agreement will be reviewed regularly to ensure it remains effective and relevant. Discussions are ongoing regarding UK participation in EU defense initiatives such as Permanent Structured Cooperation (PESCO) and the possible formation of an administrative arrangement with the European Defence Agency.
Officials from both sides have indicated that the partnership is a “first step” towards even deeper cooperation in the future, potentially paving the way for joint procurement, collaborative R&D, and integrated responses to emerging security challenges.
Broader Implications
The Security and Defence Partnership is widely seen as a breakthrough in UK-EU relations, signaling a reset after years of uncertainty following Brexit. It demonstrates that, despite political differences, both sides recognize the imperative of working together to safeguard their citizens and interests in an increasingly dangerous world.
The agreement also has significant economic implications, particularly for the UK’s defense industry, which stands to benefit from access to EU projects and funding. It is expected to support economic growth and job creation on both sides, while helping to prevent fragmentation of Europe’s defense market.
The EU, UK agree defense partnership marks a new era of strategic cooperation, reflecting shared values, interests, and responsibilities. As Europe navigates a period of profound insecurity, this partnership provides a structured, pragmatic framework for joint action—strengthening the continent’s resilience and reinforcing its contribution to global stability.
As Kaja Kallas succinctly put it,
“We are both committed to working together for our collective security, because we are all stronger when we do.”
