The ten countries within the British-led defence cooperation group Joint Expeditionary Force (JEF) have signed an agreement on deepened naval cooperation. The initiative, the Northern Navies Initiative, is intended to improve the countries' ability to conduct joint operations in the North Atlantic, the Baltic Sea and the northern maritime areas.

The agreement was signed on 10 November aboard the British aircraft carrier HMS Prince of Wales in Oslo, Norway, in connection with the International Sea Power Conference. The conference was part of the port visit that Nordic Defence Sector previously reported on.

The Royal Navy states that the cooperation covers joint planning and training, compatible equipment, and the ability to use each other's ports for maintenance and supply.

Part of the initiative concerns the integration of unmanned maritime systems and sensors, so that these can be used within other JEF countries' command and control systems. The cooperation also covers the protection of critical undersea infrastructure and the handling of hybrid threats.

The goal is for the JEF countries' naval forces to be able to act jointly at an early stage of a crisis and, if necessary, transition to NATO command. The agreement builds on a statement of intent presented in April 2026.