On 1 April 1946, the US Navy sank 24 Imperial Japanese Navy submarines in the East China Sea. This action was part of Operation “Road’s End”, in which nine more Japanese submarines would be sunk on 5 April and six more by early May. Furthermore, in May and June 1946, the Americans would use four Japanese submarines as targets near Hawaii, and on 8 May, the Australian Navy would shoot six or seven boats for the same purpose (data on numbers vary).
The Japanese navy had aircraft-carrying submarines - unique at the time - capable of carrying up to three bombers, ultra-small submarines, kamikaze-guided Kaiten torpedoes and other sophisticated naval equipment.
At the end of the war, several of Japan's most innovative and advanced submarines were sent to Hawaii for research under Operation Road's End (submarines I-400, I-401, I-201 and I-203 classes) and then sunk to prevent Soviet specialists from inspecting them.
In the post-war era, production, assembly and design techniques became almost more important than the inventions themselves. The Japanese submarines could provide the Soviet specialists with clues to the development of underwater aircraft carriers capable of striking at United States territory.
During the entire post-war period, the site of the sinking of the Japanese submarines remained classified.