The U.S. Navy intentionally sank the captured Japanese I-400 submarine in 1946 off the coast of Oahu, Hawaii. This was done to prevent the advanced technology from falling into Soviet hands during the early Cold War, as the U.S. was worried the USSR would demand access to the captured Japanese subs under the terms of the war's treaty. The I-400 was one of five Japanese submarines scuttled to keep their secrets safe. Capture: At the end of World War II, the U.S. Navy captured the I-400 and other

During World War II, Japan developed one of the war’s most daring weapons—the Seiran, a submarine-launched attack aircraft designed for surprise long-range strikes. Carried aboard massive I-400–class submarines, this hidden air power nearly altered the course of the war with its bold mission concept. A remarkable story of WWII innovation, naval aviation, and strategic surprise, the Seiran mission remains one of history’s most ambitious military experiments. 🔎 WWII history | Japanese military av