UK and Poland Sign New Security Treaty as Russian Threat Reshapes European Defence

The United Kingdom and Poland have signed a new defence and security treaty aimed at strengthening military cooperation, improving resilience against hybrid threats and reinforcing Europe’s response to Russia’s long-term challenge to regional security. The agreement, signed in London by British Prime Minister Keir Starmer and Polish Prime Minister Donald Tusk, comes as European governments continue to deepen bilateral defence ties alongside NATO frameworks.

The treaty, known as the Northolt Treaty, identifies Russia as the most significant long-term threat to Euro-Atlantic security and calls for closer cooperation between London and Warsaw in defence, foreign policy, border security, energy security and economic resilience. Both governments also reaffirmed their commitment to NATO, while stressing the need for European allies to take greater responsibility for collective security.

Starmer described the agreement as a major step forward in the UK-Poland security relationship, saying both countries face no greater challenge than Russian aggression. Tusk also underlined the importance of the partnership, framing the treaty as part of a wider effort to secure Poland, Britain and Europe against hostile threats.

A key part of the agreement focuses on defence industry cooperation. The UK and Poland are expected to work more closely on next-generation air defence capabilities, including the development of medium-range air defence missiles and related missile defence systems. The treaty also points to deeper joint procurement, expanded military exercises and closer cooperation in areas such as counter-drone warfare, electronic warfare and uncrewed systems.

The agreement also reflects the growing importance of hybrid threats in European security planning. British officials have pointed to cyberattacks, espionage, sabotage attempts and Russian-linked hostile activity across Europe as examples of threats that require faster intelligence sharing and coordinated responses. Under the treaty, the two countries aim to improve cooperation against such activity while strengthening their ability to respond in real time.

Migration and border security are also included in the pact. London and Warsaw plan to develop a joint action plan on irregular migration, with a focus on dismantling organised crime groups, targeting smuggling networks and improving border surveillance through intelligence sharing and new technologies. This broadens the treaty beyond traditional military cooperation and links defence policy with internal security challenges.

The new agreement builds on earlier UK-Poland defence arrangements signed in 2017 and 2023. However, its timing is significant. Since Russia’s full-scale invasion of Ukraine, European countries have accelerated bilateral and regional security deals, seeking to reinforce NATO’s eastern flank and reduce uncertainty over future U.S. commitments to European defence. Poland has become one of Europe’s most important frontline defence actors, while the UK is trying to strengthen its post-Brexit security role through closer ties with key European partners.

The treaty is not without criticism. Some defence analysts argue that parts of the agreement remain broad and lack detailed obligations, while others question how much it adds to previous UK-Poland commitments. Still, the political signal is clear: London and Warsaw want to present themselves as closely aligned European security partners at a time when the continent faces pressure from Russia, hybrid warfare and uncertainty over the future balance of responsibility inside NATO.

For Poland, the deal strengthens ties with one of Europe’s leading military powers and supports its wider effort to build a stronger deterrence posture. For the UK, it reinforces a strategy of rebuilding security links with European allies through bilateral treaties with countries such as France, Germany and now Poland. As Europe adapts to a more dangerous security environment, the Northolt Treaty shows how defence cooperation is increasingly moving through both NATO structures and country-to-country partnerships.