Once again, though,
why would the US have fought Japan in the late 1920's? Even a decade later, China alone wasn't enough to do it--the US didn't impose serious sanctions on Japan until after the fall of France and Holland when southeast Asia was also menaced. US resentment in 1927 was directed against the Chinese Nationalists, not Japan, because of the Nanking incident.
https://en.wikipedia.org/wiki/Nanking_incident_of_1927 US relations with Chiang did improve after he broke with the Communists, but nobody wanted to see the US go to war for him. The US was far more hostile to Soviet Russia than to Japan, yet it certainly gave no thought to going to war over the Soviet-Chinese clash in Manchuria in 1929. And of course the US would go no further than the Stimson "non-recognition' doctrine in 1931 despite the flagrant Japanese aggression. Why would it go further in, say, 1928?
You could just as well say, "well, there was War Plan Red; therefore a war with the UK was plausible."
https://en.wikipedia.org/wiki/War_Plan_Red But it wasn't! No matter how detailed a contingency plan, there isn't going to be a war unless the political basis for a war exists.