Japan's navy spent decades calling its aircraft carriers destroyers
Japan's post-war constitution renounces war, yet the country runs a navy of 160 ships and 50,800 personnel. It has managed the tension partly through careful labels: flat-decked ships built for helicopters were officially destroyers, and when they were refitted for F-35B jets in 2025 they became multi-role aircraft-carrying cruisers.
The Imperial Japanese Navy was dissolved after defeat in 1945. Some warships, the battleship Nagato among them, went to the Allies as reparations, and the rest brought soldiers home or swept mines from Japanese waters. That minesweeping fleet passed to the new Maritime Safety Agency, quietly keeping naval know-how alive. Article 9 of the 1947 constitution renounced war as a sovereign right, but the prevailing reading in Japan allows forces for self-defence, and Cold War America was glad to see Japan share the load.
The modern force was founded on 1 July 1954, starting with destroyers handed over by the United States. Its first home-built destroyer since the war, Harukaze, arrived in 1956. Facing a large Soviet submarine fleet, it concentrated on hunting submarines, and it still keeps its own diesel-electric boats among the most advanced anywhere by retiring them early and replacing them with newer designs. The Ōryū, christened in 2018, was Japan's first submarine to run on lithium-ion batteries.
After the Cold War its horizons widened. Under international pressure it sent minesweepers to the Persian Gulf in 1991, and from 1993 it supported UN peacekeeping, beginning with Cambodia. The same year it commissioned Kongō, its first Aegis-equipped destroyer, and a ship-based missile defence system was successfully test-fired on 18 December 2007.
The word games matter because the forces may not own attack aircraft carriers. The government defines those narrowly, as ships built only for nuclear bombers, so carriers for helicopters or ordinary fighters are not banned. Lloyd's Register nevertheless classed the Hyūga-class helicopter destroyer as a helicopter carrier. A retired vice-admiral argued in 2019 that the two Izumo ships, each able to carry about 10 F-35Bs, were too few for real combat and that at least four were needed.
Source: Japan Maritime Self-Defense Force
