Its not as simple as you portray. There was a lot more going on than most know. This book is full of the background, including tons of original documents.
Magic: The Untold Story of U.S. Intelligence and the Evacuation of Japanese Residents from the West Coast During WWII
https://www.amazon.com/Magic-Intelligence-Evacuation-Japanese-Residents/dp/0960273611
Roosevelt and the upper crust of DC government, knew the date of an attack on Pearl. They were also reading cables. Roosevelt was one helluva manipulator, and the press covered for him just like today.