Japan Maritime Self-Defense Force Advances Aircraft Carrier Conversion with Successful “KAGA” Modification

The Japan Maritime Self-Defense Force (JMSDF) successfully completed the first phase of modifications on the JS Kaga (DDH-184), marking a significant milestone in the conversion of the helicopter carrier into an aircraft carrier. The project, initiated in March 2022, aims to equip the vessel with the operational capabilities required for hosting F-35B aircraft. The completion of the initial modification work on March 29 signifies the JMSDF’s commitment to bolstering its naval capabilities. Moving forward, the focus will remain on executing further necessary modifications on the “IZUMO” class destroyer to ensure seamless integration of the short take-off and vertical-landing (STOVL) F-35B aircraft.

JS Kaga (DDH-184) is a helicopter carrier being converted into an aircraft carrier beginning in March, 2022. Officially classified as a multi-purpose operation destroyer, she is the second ship in the Izumo class of the JMSDF, the other being JS Izumo. Kaga was intended to replace the aging Shirane-class destroyer Kurama Her namesake arises from Kaga Province in present-day Ishikawa Prefecture. The ship bears the same name as the World War II-era Kaga, the Tosa-class battleship turned aircraft carrier that was produced in 1928 and participated in the attack on Pearl Harbor. Kaga was built as part of a wider Japanese military buildup, triggered by heightened Sino-Japanese tensions regarding the contested ownership of the Senkaku Islands.

Kaga is 812 feet (247 m) long, and displaces 27,000 tons, making her the largest ship in the Japan Maritime Self-Defense Force. The ship can host up to 28 aircraft, or 14 helicopters. While Japanese nomenclature calls Kaga a “multi-purpose operation destroyer”, its main purpose is destroying enemy submarines. The ship is equipped with two Phalanx CiWS (close-in weapon systems) and two SeaRAM CiWS for her defense. Despite this, only 7 anti-submarine warfare helicopters and 2 search and rescue helicopters are planned for the initial aircraft complement. 400 troops and 50 3.5-ton trucks (or equivalent equipment) can also be carried. Kaga features were intended to support fixed-wing aircraft such as the Bell-Boeing V-22 Osprey and Lockheed Martin F-35 Lightning II.

In 2019, it was reported that Prime Minister Shinzo Abe approved a ¥26.2 trillion (US$238.72 billion) five-year defense budget, which included the upgrade of Izumo and Kaga and the purchase of a combined 147 F-35A and F-35B stealth fighters. Kaga began her initial modifications in March 2022 at the Japan Marine United (JMU) shipyard in Kure, Hiroshima Prefecture. The proposed modification of Kaga will be more extensive than for her sister ship (and significantly more expensive) and includes changes to the shape of the bow. The initial modification of Kaga is expected to take 14 months, followed by a second modification of the ship’s interior, which is expected to begin in March 2027.