On November 3, 1941, the Japanese government informed fleet commanders of a top-secret plan: In 34 days, Japanese pilots were to bomb Pearl Harbor. Tension between the U.S. and Japan increased when Japan had invaded Indochina in 1940. The U.S. retaliated by seizing Japanese assets in the U.S. and closing the Panama Canal to the Japanese. The Japanese determined that these were acts of aggression, and they decided to deal the first blow by bombing the Hawaiian U.S. Naval Base.
