Warsaw and London will also work on a new joint action plan on irregular migration that “will discuss how to boost border security and dismantle organised crime groups,” according to the treaty.
The agreement, which builds on similar pacts between the two countries signed in 2017 and 2023, is the latest in a long line of bilateral deals as European countries look to reinforce relationships with allies beyond NATO.
Of the 169 multilateral defense deals signed by EU countries, the U.K. and Ukraine since 2014, 135 were signed after Moscow’s all-out war began in 2022, with 36 signed in 2025 alone.
The continent’s biggest military powers — the U.K., France, Italy, Germany and Poland — are signing deals that bind their defense industries and militaries into a tighter web of cooperation. Poland plans to sign a similar deal with Germany next month.
Ed Arnold, a defense adviser at The D Group consultancy and a former NATO official, said the Northolt agreement is part of a broader effort by Starmer to realign Britain with the EU, and could help signal demand to defense companies for greater production in both countries.
Yet the text, which he argued is “deliberately … vague on detail,” has few granular obligations and adds little to previous iterations. It’s more about London showing it is stepping up on defense despite repeated delays to its defense investment plan. “It’s a lot of politicking,” Arnold said.