The Kensington Treaty: UK–Germany’s Strategic Reconnection After Brexit

The signing of the Kensington Treaty on July 17, 2025, by UK Prime Minister Keir Starmer and German Chancellor Friedrich Merz stands as a pivotal moment in post-Brexit European diplomacy. This formal bilateral agreement, the first of its kind between the United Kingdom and Germany since the end of World War II, was concluded amid the elegant surroundings of the Victoria and Albert Museum in London, a venue that symbolically bridges cultural heritage with forward-looking collaboration. Officially titled the Treaty between the United Kingdom of Great Britain and Northern Ireland and the Federal Republic of Germany on Friendship and Bilateral Cooperation, the document represents a deliberate and comprehensive effort to rebuild and strengthen ties that had grown distant following Britain’s departure from the European Union.

At its core, the treaty establishes a framework for deepened partnership across several critical domains, reflecting a shared recognition that the two nations face common challenges in an increasingly uncertain global environment. One of the most prominent elements is the commitment to mutual assistance in matters of security and defense. The agreement includes a clause pledging support in the event of an armed attack, which serves to reinforce and complement existing obligations under NATO while emphasizing the bilateral dimension of European security. This provision underscores a pragmatic response to evolving threats, particularly Russia’s continued aggression in Ukraine and broader concerns about the reliability of transatlantic commitments, especially amid perceived uncertainties in U.S. foreign policy directions.

Beyond symbolic declarations, the treaty translates into concrete initiatives aimed at enhancing defense industrial cooperation. Both countries have agreed to pursue joint production of key military platforms, building on longstanding collaborations such as those involving Typhoon fighter jets and Boxer armored vehicles. Plans also extend to long-range precision missiles and other advanced systems, with a focus on coordinated export strategies to strengthen economic returns and global competitiveness. A notable practical step includes the establishment of a German drone manufacturing facility in Swindon, which promises to foster technological innovation, create high-skilled employment opportunities, and deepen supply-chain integration between British and German industries. These efforts highlight a strategic intent to leverage complementary strengths—Britain’s expertise in certain aerospace and naval technologies alongside Germany’s engineering prowess and manufacturing scale—to build resilient defense capabilities independent of broader multilateral constraints.

The treaty also addresses pressing domestic and cross-border issues, particularly irregular migration. Germany has committed to criminalizing activities that facilitate people-smuggling operations, targeting loopholes that have allowed the assembly, storage, or transport of small boats destined for dangerous Channel crossings into the United Kingdom. This legal alignment is designed to bolster UK enforcement capabilities and disrupt organized criminal networks more effectively. By harmonizing approaches to a shared humanitarian and security challenge, the agreement demonstrates how bilateral pragmatism can yield tangible results where multilateral frameworks have sometimes fallen short. People-to-people connections form another vital strand of the treaty, aiming to restore and expand mobility that diminished sharply after Brexit. Measures include enabling UK passport holders to utilize Germany’s automated e-gates starting in August 2025, thereby easing travel for tourists, business travelers, and families. Visa-free arrangements for school trips and expanded youth mobility programs are slated for implementation by the end of the year, fostering educational and cultural exchanges that rebuild interpersonal ties between younger generations. Looking further ahead, discussions have begun on establishing a direct high-speed rail connection between London and Berlin, with a projected timeline of up to ten years for realization. Such infrastructure would not only enhance physical connectivity but also symbolize a tangible reconnection across the North Sea, reducing reliance on air travel and promoting sustainable links in an era of climate considerations.

The broader strategic context of the Kensington Treaty reveals a deliberate reset in UK-German relations after years of post-Brexit strain. For much of the intervening period, bilateral engagement had been overshadowed by negotiations over trade barriers, regulatory divergence, and the mechanics of separation from EU structures. The treaty marks a conscious shift toward proactive partnership, positioning London and Berlin as influential voices—alongside France within the informal E3 grouping—in shaping European policy and security architecture even as the UK remains outside the EU. This approach aligns with a growing European emphasis on strategic autonomy, driven by the need to prepare for scenarios where external alliances may prove less dependable.

Leaders on both sides have framed the agreement in terms that emphasize its timeliness and necessity. Chancellor Merz described the long absence of such a formal bilateral treaty since 1945 as an historical oversight now being corrected, highlighting the depth of shared interests that transcend past divisions. Prime Minister Starmer, in turn, presented it as a clear statement of intent for a confident post-Brexit Britain—one that pursues reintegration through targeted alliances rather than institutional membership. This narrative reflects a maturing understanding that sovereignty and cooperation are not mutually exclusive, but can reinforce one another when grounded in mutual benefit. Of course, translating ambitious commitments into reality will present significant challenges. Coordinating complex defense production schedules across different procurement systems and industrial bases demands sustained political will and administrative precision. Legal harmonization on migration policies could encounter domestic pushback, particularly in Germany where changes to criminal law or border procedures might spark debate over humanitarian implications or federal competencies. In the UK, critics from more Euroskeptic quarters may question whether closer alignment with a major EU member risks diluting hard-won independence or inadvertently pulling Britain toward continental orbits. Geopolitically, the treaty must navigate the delicate balance of strengthening bilateral ties without creating redundancies or tensions within NATO or emerging European defense initiatives.

Despite these hurdles, the Kensington Treaty embodies a forward-looking pragmatism that prioritizes shared purpose over ideological divides. It signals that in an era defined by great-power competition, persistent regional conflicts, and questions over global leadership, established European democracies can adapt by forging resilient partnerships. Rather than seeking a return to pre-Brexit arrangements, the agreement charts a path of strategic re-anchoring, where the UK and Germany collaborate closely on defense, economic security, controlled migration, and human connections. As the continent grapples with uncertainty—from the war in Ukraine to potential shifts in American engagement—this bilateral accord offers a model of constructive engagement, demonstrating that deep cooperation remains possible and indeed essential for safeguarding prosperity and stability in Europe. In doing so, it not only mends a relationship strained by recent history but also contributes meaningfully to the broader effort of building a more self-reliant and cohesive European security landscape.