One of those planes almost dirty bombed San Francisco near the end of WWII.
The Japanese had concocted a plan to launch M6A1 Seiran floatplane bombers from their huge I-400 class subs to drop bombs loaded with biological agents such as plaque and Anthrax on the West Coast of the US. The ships had sailed with a target date of 15 August 1945. Only the end of the war on 14 August occasioned their recall before they reached landfall.