[PvK]

The Sen Toku's bomber ability might not be necessary. With a nuclear weapon, one doesn't really need to fly it on a seaplane to be effective against coastal cities such as Los Angeles, San Francisco, Seattle, Tacoma, Vancouver B.C., etc.. If one has a long-range submarine and suicidal crew and/or trust in timed automation systems. Just sail a sub next to the city, surface, detonate.