Japan attacked Pearl Harbor on December 7, 1941, at approximately 8:00 A.M. Hawaiian time.
The United States knew an attack was coming, but we didn’t know where it would occur. The United States had broken the Japanese secret code. As a result, we knew that Japan was planning to attack us. On the morning of the attack, about an hour before the attack began, our radar picked up a group of planes. However, our military personnel believed they were American B-17 planes coming from California. Therefore, no action was taken.
Japan was upset with us because we stopped selling them supplies they needed to carry out their military objectives. They needed oil and scrap metal from us, and we stopped selling those items to them with the passage of the Export Control Act in 1940. We also froze their assets in our banks in 1941 as Japan became more aggressive in Asia and in the Pacific region.
December 7, 1941, is a “date which live in infamy” President Roosevelt declared in his address to Congress.