"Instead of being tried for war crimes, the researchers involved in Unit 731 were given immunity by the U.S. in exchange for their data on human experimentation."

"During the final months of World War II, Japan planned to use plague as a biological weapon against San Diego, California. The plan was scheduled to launch on September 22, 1945, but Japan surrendered five weeks earlier."

Related discussion thread from 2015 -

Why Japanese leaders attacked Pearl Harbor

https://news.ycombinator.com/item?id=10683059

Holymoly