British Prime Minister Keir Starmer and Polish counterpart Donald Tusk signed a bilateral defence treaty in London on Wednesday, pledging to combine military expertise and industrial capacity, including the joint development of next-generation weapons. The agreement also provides for large-scale land force exercises, expanded use of uncrewed systems along NATO's eastern flank, and closer cooperation on cybersecurity, organised crime, and migration. The signing came as the head of GCHQ (Britain's signals intelligence agency) warned that Russia is "relentlessly" targeting critical infrastructure and democratic processes across Europe, underscoring the urgency that drove both governments to the deal.