The first Japanese aircraft carrier in 75 years begins conversion

At the Japan Maritime United Isogo shipyard in Yokohama, JS Izumo DDH-183 has entered into the process of being converted to a genuine aircraft carrier. Currently designated as a helicopter destroyer, Izumo does not have the capability to operate fixed-wing aircraft from her deck. In the first of two main stages of her conversion, coinciding with her regular 5-year refit and overhaul programs, Izumo will receive upgrades to accommodate Japan's new F-35B Lightning II fighter jets.

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Following the surrender of the Japanese Empire in WWII, the Imperial Japanese Navy had only three aircraft carriers left in its fleet: Hōshō survived the war as a training carrier, Junyō had been damaged during the Battle of the Philippine Sea and was awaiting repairs, and Katsuragi could not be equipped with enough fuel, aircraft, or pilots by the time she was completed in late 1944. Hōshō and Katsuragi would ferry Japanese servicemen back to Japan until 1947 when all three surviving carriers, along with three unfinished carriers, were scrapped.

Article 9 of Japan's post-war 1947 Constitution renounced war as "a sovereign right of the nation and the threat or use of force as a means of settling international disputes." As a result, a Japanese Navy could not be formed as a military branch for power projection. Rather, Japan created the Japan Maritime Self-Defense Force as a branch of the Japan Self-Defense Forces in 1954. Though the JMSDF is tasked with the naval defense of the Japanese islands, Japan's partnership with Western countries during the Cold War led its focus on anti-submarine warfare to combat the Soviet Navy.

In 2007, Japan launched two Hyūga-class helicopter destroyers. With their flat-top decks, the Hyūgas were often called Japan's first aircraft carriers since WWII. However, they were only capable of operating rotary-wing aircraft from their decks and had no launch or recovery capabilities for even VTOL fixed-wing aircraft. Doctrinally, the Hyūgas were used as flagships for anti-submarine operations.

Launched in 2013, Izumo is the lead ship in her class and the replacement for the Hyūgas. Displacing 27,000 long tons fully loaded, Izumo and her sister ship, Kaga DDH-184, are the largest surface combatants in the JMSDF. Like the Hyūgas before, Izumo is a helicopter destroyer that carries rotary-wing aircraft and is tasked with anti-submarine operations. However, in December 2018, the Japanese government announced that Izumo would be converted to operate fixed-wing aircraft in accordance with new defense guidelines.

Japan's updated defense policy called for a more cohesive, flexible, and multidimensional force in response to growing Chinese aggression in the South China Sea and the completion of the Shandong, China's first domestically-built aircraft carrier.

Estimated at million, the modifications to Izumo include a cleared and reinforced flight deck to support additional weight, added aircraft guidance lights, and heat-resistant deck sections to allow for vertical landings by F-35Bs. At this time, no specifications have been released regarding a ski-jump, angled flight deck, or catapults.

The first stage of modifications will be evaluated in a series of tests and sea trials following completion. Final modifications in stage two of the ship's conversion are expected to take place in FY 2025 during the next overhaul and further evaluation. Izumo's sister ship, Kaga, will also be converted to an aircraft carrier, though no timeline has been released for her modifications.

The conversion to accept fixed-wing aircraft will provide Izumo and Kaga increased interoperability with allies. As aircraft carriers, they would be able to support not only Japanese F-35Bs, but also American F-35Bs and V-22 Ospreys. During a meeting on March 26, 2019 with General Robert Neller, Commandant of the United States Marine Corps, the Japanese government asked for guidance and advice on how to best operate F-35Bs from the decks of the future carriers; General Neller said that he would, "help as much as possible."

On the creation of the new carriers and their joint capabilities, Japanese Defense Minister Takeshi Iwaya is quoted as saying, "The Izumo-class aircraft carrier role is to strengthen the air defense in the Pacific Ocean and to ensure the safety of the Self-Defense Force pilots. There may be no runway available for the US aircraft in an emergency."

The conversion of the helicopter destroyers into aircraft carriers has received some opposition both domestically in Japan and abroad. Some people fear that the new capabilities will be a catalyst for future Japanese military expansion and aggression. Already, the JMSDF is the fourth largest world naval power by tonnage, behind only China, Russia, and the United States. However, the Japanese government remains adamant that the modernization efforts are only meant to bolster the country's self-defense capability against growing threats from China.