Japan and the United Kingdom are deepening their defense ties as security challenges grow across the Indo-Pacific and Europe. Following the U.K. Carrier Strike Group’s three-week visit to Japan in August and September 2025, which included joint fighter jet training over the Sea of Japan, the Japan Air Self-Defense Force (JASDF) dispatched F-15 fighters and support aircraft to Europe and North America for unit-to-unit exchanges.
Meanwhile, Japan and the U.K., along with Italy, are developing a fighter jet under their Global Combat Air Program (GCAP).
The JASDF deployed four F-15s, supported by C-2 transport and KC-767 and KC-46A refueling aircraft, to Canada, Germany, the U.K. and the United States for two weeks beginning in mid-September, according to Japanese Defense Minister Gen Nakatani. The aircraft were set to train with each nation’s air force.
“By dispatching Air Self-Defense Force fighter jets on this goodwill visit, we are embodying our shared recognition that security in the Euro-Atlantic and Indo-Pacific regions is inseparable and interconnected,” Nakatani said, according to Japan’s Defense Ministry.
Nakatani met with U.K. Defence Secretary John Healey in Tokyo in late August 2025. The leaders reaffirmed their countries’ Enhanced Global Strategic Partnership and agreed to deepen cooperation across exercises, the space and cyber domains, and defense technology initiatives such as the GCAP, according to a statement. Under a 2023 reciprocal access agreement, each nation’s forces can deploy to the other’s territory for training and joint exercises.
During the U.K. strike group’s visit to the region, the JASDF deployed four F-35A stealth fighters and eight F-15s to join four U.K. F-35B fighters operating from the Royal Navy aircraft carrier HMS Prince of Wales for tactical drills over the Sea of Japan.
Also as part of the eight-month, U.K.-led multinational mission Operation Highmast, HMS Prince of Wales hosted the Pacific Future Forum. The international summit, which brought together military, government and industry leaders, focused on strengthening defense, technology and trade relationships among regional democracies.
At the forum, Healey called Japan “the U.K.’s closest security ally in Asia” and said their defense relationship is vital to regional and global security.
“I know Japan sees Britain as its closest security partner in Europe,” he said. “So in every domain, we’re putting in the hard work now so that if ever we are called on to work together in a time of crisis, we know we can. And so do potential adversaries.”
The GCAP, which aims to deploy a sixth-generation fighter by 2035, was a central topic at the forum. Healey announced the Edgewing industrial venture involving defense firms BAE Systems of the U.K., Italy’s Leonardo and the Japan Aircraft Industrial Enhancement Co. The U.K.-based Rolls-Royce announced in September 2025 that it has joined the GCAP to speed development of the fighter’s power and propulsion system.
“GCAP grew out of our common assessment of threats, our respect for each other’s technology, and our shared imperative and timeline for introducing the next generation of capability,” Healey said.
