Pearl Harbor exposed Japan's strategic dilemma: it could damage the United States, but could not match Allied industrial depth over a long war. Infrastructure underpins logistics, and logistics makes sustained naval power possible. A very long-range submarine offered a way to bypass enemy forces and threaten the systems that sustained them rather than seek an unwinnable stand-up fight. This approach sought leverage against Allied mass by attacking its foundations instead of trying to equal the number of ships it produced.
Notable Point · 4:21-7:28
A weapon for offsetting American industrial mass
The I-400 concept is set against Japan's attempt to overcome the industrial and logistical scale available to the United States and Britain.