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