Japanese submarine minelayers against the U.S. West Coast

How would a Japanese submarine force built around minelaying affect the United States?

It could complicate West Coast operations, but the effect would depend heavily on coastal geography, waterway access, and whether mines could be delivered beyond exposed sea approaches.

A Japanese fleet dominated by minelayers and aircraft-carrying submarines would make the American West Coast a contested operational area. The East Coast's intercoastal waterway network, by contrast, could help move vessels away from exposed sea routes. Mines placed inside such protected waterways would be harder to deliver because attackers might need to land boats and carry weapons across beaches. The effect would depend on geography and access rather than on submarine numbers alone.