The next phase of the Royal Navy’s Carrier Strike Group 25 deployment, Operation Highmast, will focus on integrated air operations in the Indo-Pacific, with British and Japanese forces preparing for combined F-35B activities at sea, according to a Ministry of Defence update.
Both nations operate the short take-off and vertical landing (STOVL) variant of the fifth-generation stealth fighter, the F-35B. While the UK has deployed the aircraft operationally since 2018, Japan is still in the early stages of integrating the platform into its maritime forces.
This week’s joint operations will see aircraft and crews from both countries exercising side by side from sea, building interoperability and laying the groundwork for future cooperation.
The joint phase will last a week, after which the UK task group will split. Elements of the force will proceed to South Korea, while HMS Prince of Wales and her escorts are scheduled to continue to Japan.
The two navies have been steadily advancing air-sea integration. In 2024, a British F-35 pilot, Lieutenant Commander Baker, made history by landing on a Japanese Maritime Self-Defense Force (JMSDF) vessel for the first time. The flight, part of Lt. Cmdr Baker’s work with the U.S. Patuxent River Integrated Test Force, marked a symbolic step forward in UK-Japan defence cooperation.
Japan recently adapted its Izumo-class helicopter carriers to operate the F-35B. This includes structural modifications and heat-resistant deck coatings to handle the STOVL aircraft’s vertical thrust. The joint work with the UK Carrier Strike Group is seen as a key opportunity to advance Japan’s ability to project power at sea.
Operation Highmast forms part of the broader UK strategy of persistent presence in the Indo-Pacific, aimed at deepening security ties with regional allies through practical exercises, logistics integration and multilateral deployments.
A really good step forward. Combined operatons in he Far East with Japan and other allies is a real force multiplier.