The Japan Maritime Self-Defense Force's Kaga DDH184 Advances F-35B Operational Readiness for 2026 IPD26
Tanaka TakashiJS Kaga DDH184 Advances F-35B Operational Readiness for IPD26 in 2026
The photo of the destroyer "Kaga" departing from Kure is not just a scene of departure. According to USNI News, on June 9, "Kaga" DDH-184 departed as part of the second surface unit for the 2026 Indo-Pacific Deployment, or IPD26, alongside the destroyer "Fuyuzuki" DD-118 and the supply ship "Mashu" AOE-425. The Japan Maritime Self-Defense Force has not yet detailed its specific operational plans. Here, there is rather something noteworthy to observe.
Composition of the Second Surface Unit
The IPD26 materials released by the Maritime Staff Office on April 14 state that the deployment period is from April 13 to September 16, and the second surface unit consists of the three ships: "Kaga," "Fuyuzuki," and "Mashu." In comparison, the first surface unit consists of "Ise," "Ikazuchi," and "Shimokita," while the third surface unit is "Kongo." This indicates that the second surface unit is clearly organized with a focus on air operations and at-sea replenishment.
"Kaga" is an Izumo-class destroyer with a length of 248 meters and is not a fleet air defense ship. "Fuyuzuki" is an Akizuki-class destroyer responsible for air and anti-submarine defense, while "Mashu" is a supply ship that supports range and training sustainability. In other words, these three ships are not a combination for a demonstration cruise but are close to the minimum unit necessary to continue air-related training in distant waters for a certain period.
Discrepancies in the RIMPAC Roster
Interestingly, the only Japanese ship confirmed on the U.S. Pacific Fleet's RIMPAC 2026 participant list is "Kongo" DDG-173. RIMPAC is scheduled to take place from June 24 to July 31, involving 31 countries, about 40 ships, 5 submarines, over 140 aircraft, and more than 25,000 personnel, but at least on the public list, "Kaga," "Fuyuzuki," and "Mashu" are not included.
This seems to contradict the JMSDF materials that list RIMPAC, Pacific Dragon, and Pacific Vanguard as major participating exercises. However, in the author's view, this may indicate a change in mission allocation rather than a contradiction. "Kongo" is aligned with RIMPAC's emphasis on ballistic missile defense and air defense integration, while "Kaga" is tasked with practical training related to F-35B operations in a different maritime area. Considering this, the gaps in the public information become quite explainable.
Practical Stage of F-35B Training
USNI News reported on May 20 that the U.S. Marine Corps F-35B is expected to conduct landing and takeoff training on "Kaga" in June. According to the report, "Kaga" was scheduled to call at Iwakuni Air Base from June 1 to 4 to load the necessary equipment for F-35B operations. Japan plans to introduce 42 F-35Bs, with the first three delivered the previous year and another three this year.
It is important to note that Japan's F-35Bs are equipment of the Air Self-Defense Force, while the ship belongs to the Maritime Self-Defense Force, indicating a systemic separation. Carrier operations cannot be established merely by heat treatment of the deck or changes to the bow shape. The integration of aviation fuel, munitions, maintenance personnel, control, weather assessment, safety margins during landing recovery, and shared procedures between Japan and the U.S. must all work together to enhance fleet capability.
- IPD26 period is from April 13 to September 16, 2026
- The second surface unit consists of the three ships: "Kaga," "Fuyuzuki," and "Mashu"
- In the public participant list for RIMPAC 2026, the only Japanese ship is "Kongo"
- "Kaga" is expected to complete its second phase modifications by March 2029
Implications for Southwest Defense
To dismiss the aircraft carrier conversion of "Kaga" simply as a counter to China is superficial. More practically, the question is whether Japan can have options for air operations that do not solely rely on fixed bases for the protection of SLOCs, or sea lines of communication, from the Nansei Islands to the Philippine Sea. Bases such as Naha, Chikushino, Nittahara, and Iwakuni are significant, but in times of crisis, runways, fuel facilities, and ammunition depots may all come under simultaneous pressure.
In such cases, destroyers capable of carrying F-35Bs create opportunities to connect with the U.S. Marine Corps' distributed operations. However, this is not simply a matter of adding one more small aircraft carrier. If "Kaga" goes into maintenance or modification, the actual usable flight deck will suddenly shrink. What the JMSDF is trying to confirm during IPD26 is not glamorous carrier operations but how much of the logistics, maintenance, and air control between Japan and the U.S. can be integrated into daily procedures.
Based on public information alone, the current departure of "Kaga" is not a display of completed carrier capabilities but rather a test to measure the incomplete integrated operational capabilities at sea.
During the Cold War, the JMSDF primarily served to support U.S. carrier strike groups through anti-submarine warfare and SLOC protection. The "Kaga" of 2026 has entered a stage where it can welcome the Air Self-Defense Force and U.S. Marine Corps onto its deck while retaining that memory. The true challenge is not for the ship's form to approach that of an aircraft carrier. It is about which command will decide which air units to embark on "Kaga" in the first 72 hours of a crisis.
Key References
The Japan Maritime Self-Defense Force (JMSDF) deployed the 2nd Surface Unit, consisting of Kaga, Fuyuzuki, and Mashu, from Kure for training and operations with F-35B aircraft. This deployment is part of the Indo-Pacific Deployment 2026, scheduled from April 13 to September 16, 2026. Notably, only the Kongo is listed as a participating Japanese ship in RIMPAC 2026, indicating a shift in mission focus.
- The 2nd Surface Unit consists of Kaga, Fuyuzuki, and Mashu.
- Kaga is preparing for F-35B operations during the IPD26 deployment.
- Deployment period is from April 13, 2026, to September 16, 2026.
- RIMPAC 2026 only lists Kongo as the participating Japanese ship.
- Japan plans to acquire 42 F-35B aircraft, with several already delivered.