Japanese carrier JS Kaga hosts first British F-35B landings during major Indo-Pacific allied exercise.

Between August 4 and 12, 2025, the Japan Maritime Self-Defense Force participated in a major multilateral exercise in the Western Pacific, involving navies from Japan, the United Kingdom, the United States, Australia, Spain, and Norway. The objectives set by the JMSDF were to improve tactical capabilities in complex drills that covered anti-submarine warfare, cross-deck evolutions, coordinated flight operations, and combined photographic exercises, with assets from all six participating nations involved in integrated serials over nine days of operations. A notable event came when British and American F-35B Lightning II fighter jets conducted landings and take-offs from the JS Kaga’s deck, marking the first time a UK fighter had ever landed on a Japanese warship.
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During the cross-deck phase on August 8, 2025, two British F-35Bs from 809 NAS and two American F-35Bs from VMFA-242 landed on and launched from the JS Kaga, marking the first time a British fighter operated from a Japanese warship during exercises. (Picture source: British Navy)

Participating units included, for Japan, the helicopter‑carrier/light aircraft carrier JS Kaga, the Akizuki‑class destroyer JS Teruzuki, and an unnamed JMSDF submarine. The UK Carrier Strike Group joined the event as part of Operation Highmast, bringing the HMS Prince of Wales, a Queen Elizabeth-class aircraft carrier, the HMS Dauntless, a Type 45 destroyer, the HMS Richmond, a Type 23 frigate, and the RFA Tidespring, a replenishment tanker. Australia, for its part, provided the HMAS Brisbane, a Hobart-class air-warfare destroyer, when Norway fielded the HNoMS Roald Amundsen, a Fridtjof Nansen-class frigate, and Spain sent the SPS Méndez Núñez, an F-100-class guided-missile frigate. Finally, the US contingent included the USS George Washington, a Nimitz-class aircraft carrier, the USS Robert Smalls, a Ticonderoga-class guided-missile cruiser, the USS Shoup, an Arleigh Burke-class destroyer, and the USS America, an America-class amphibious assault ship.

In coordination with the US Navy’s George Washington Carrier Strike Group, the US Marine Corps Amphibious Ready Group centered on USS America, and Kaga’s own task group, a total of 11 ships and 23 aircraft conducted interoperability training. On 8 August 2025, two British F-35B Lightning II jets from 809 Naval Air Squadron and two USMC F-35Bs from VMFA-242 landed on and launched from Kaga, marking the first time a UK fighter aircraft had operated from a Japanese warship. The drills also included tactical intercepts, a UK fighter maritime strike serial, and air combat maneuvers, alongside multinational flypasts and cross-embarkation of personnel to improve mutual understanding. An emergency diversion occurred when a UK F-35B landed at Kagoshima Airport following an engineering issue, remaining on the ground for inspection during the exercise. The activity concluded with HMS Prince of Wales and HMS Dauntless entering Yokosuka Naval Base for a scheduled visit, while HMS Richmond and RFA Tidespring continued to Busan, Republic of Korea, and SPS Méndez Núñez transitioned back to Spanish command for a stopover in the Philippines before returning to Spain.

The wider context of the exercise included earlier multinational training in 2025, such as Exercise Pacific Stellar in February and Talisman Sabre in July, in which both George Washington and Prince of Wales took part. These earlier drills emphasized large-scale allied operations, and the August exercise extended the scope of cooperation by integrating fifth-generation aircraft on Japan’s largest surface ships. Commodore James Blackmore, Commander of the UK Carrier Strike Group, stated that bringing together large-deck ships from Japan, the UK, and the US, with escorts from Spain, Norway, and Australia, demonstrated interoperability at close range. The Spanish frigate Méndez Núñez carried out joint operations with Kaga and Teruzuki, including liaison officer exchanges that both navies described as improving integration. The series of deployments and visits tied to Operation Highmast also included future port calls in Tokyo and Busan, as well as a Pacific Future Forum and a Defence and Security Industry Day in Japan, broadening the political and industrial dimensions of the naval engagement.

The Izumo-class, to which JS Kaga belongs, was conceived in the 2000s as part of a mid-term defense program to replace the aging Shirane-class destroyers. The class was designated as helicopter destroyers or multi-purpose operation destroyers, with the capability to embark helicopters for anti-submarine and search-and-rescue roles, as well as transport troops and vehicles. However, early design features, such as a large flat flight deck, suggested future adaptability for fixed-wing aircraft. The program produced two ships, JS Izumo, commissioned in 2015, and JS Kaga, commissioned in 2017, both built at Japan Marine United shipyards. Each ship measures 248 meters in length, displaces around 27,000 tons at full load, and incorporates five landing spots for simultaneous helicopter operations. Initially intended to embark up to 14 helicopters, later modifications were planned to support the operation of the F-35B short take-off and vertical landing aircraft.

The JS Kaga’s conversion program began with an initial phase at JMU Kure in March 2022 that was more extensive than the work first done on sister ship Izumo, including reshaping the bow to a rectangular form and other air operations changes; that phase was completed in early 2024. (Picture source: Japanese Navy)

JS Kaga, hull number DDH-184, was laid down in October 2013, launched in August 2015, and commissioned in March 2017. Construction cost was approximately $1.05 billion, and her namesake refers to Kaga Province, although the ship’s name is written in hiragana rather than kanji, distinguishing it from her World War II predecessor. At 248 meters in length and 38 meters in beam, she is the largest ship in the JMSDF. Propulsion is provided by four General Electric/IHI LM2500IEC gas turbines on two shafts, producing speeds over 30 knots. Sensors and combat systems include the OYQ-12 combat direction system, FCS-3 fire control, OPS-50 AESA radar, OPS-28 surface search radar, and OQQ-23 bow sonar, complemented by the NOLQ-3D-1 electronic warfare suite and various decoy systems. Armament is limited to two Phalanx CIWS and two SeaRAM mounts for close-in defense.

The JS Kaga can embark up to 28 aircraft, although the initial configuration provided for seven anti-submarine warfare helicopters and two search-and-rescue helicopters. In addition, the ship can accommodate 400 troops and 50 vehicles such as 3.5-ton trucks, giving her a limited transport role. Her flat deck allows helicopter operations similar to amphibious assault ships, and while lacking a ski-jump ramp, later modifications have reshaped her bow to accommodate the safe operation of F-35B aircraft. Since commissioning, Kaga has taken part in multiple deployments, including Indo-Southeast Asia exercises in 2018 and joint operations with US and allied navies. In May 2019, the ship hosted US President Donald Trump and Japanese Prime Minister Shinzo Abe during a visit to Yokosuka, illustrating her use for high-profile diplomatic functions in addition to operational duties.

The conversion of Kaga into a ship capable of fixed-wing operations began in March 2022 at JMU Kure, and before its conversion, this ship's cost was valued at approximately ¥115 billion, or about US$1.05 billion. Unlike her sister Izumo, Kaga’s modifications included a more extensive reshaping of the bow to a rectangular form and further changes to internal compartments to support F-35B operations. The first phase, focused on external modifications, was completed in early 2024, followed by flight trials in October 2024 off San Diego, where US Marine Corps F-35Bs successfully landed and launched from her deck. The second phase, involving interior changes, is scheduled to begin in late 2026 and to be completed by the end of fiscal year 2027. Once finished, Kaga will join Izumo in operating F-35Bs, extending the reach of the JMSDF into fixed-wing carrier aviation for the first time since the Second World War.

Japan plans to acquire 42 F-35B aircraft to be based initially at Nyutabaru Air Base in Kyushu, near Kaga’s home port of Kure. Deliveries began in 2024, with plans to establish a squadron of about 20 aircraft by 2025, with further deliveries continuing through 2028. A new base is under construction on Mageshima to support F-35B operations, although it is not expected to be completed before 2030. The integration of F-35Bs with the Izumo-class is a central element of Japan’s defense modernization program, part of a larger procurement of 147 F-35s that includes both A and B variants. For Kaga, this represents a transition from a helicopter destroyer to a light carrier, positioning her as a regional asset comparable in size to Italy’s Cavour, though smaller than US supercarriers such as the Nimitz class. Completion of her conversion is scheduled to enable routine F-35B operations from 2028.