Hideki Tojo, an Army militant, became Prime Minister on October 16, 1941. His emissaries in Washington, Kichisaburo Nomura and Saburo Kurusu (whose wife was American), made U.S. Secretary of State Cordell Hull uncomfortable. As the two Japanese delivered increasingly hostile messages, with their bows and smiles, Hull began to think they were deceptive.
A primary mover behind Japan’s expansion south of her home islands, Tojo favored an attack on Pearl Harbor. But as war seemed more probable than possible, high-ranking American officials thought American troops in the Philippines were more vulnerable than those in Pearl Harbor. They did not know about "Operation Hawaii" (also called "Operation Z"), Japan’s carefully orchestrated plan created by Lt. Commander Minoru Genda.
Rumors of war increased. By December 4, the Chicago Tribune’s lead story screamed its frightening headline:
F.D.R.’s War Plans!
To this day some historians believe President Roosevelt engineered what happened at Pearl Harbor. But it’s fair to ask: Why would someone who wanted to enter the fight be willing to destroy the means by which he would win that fight? One possible answer: The President didn’t think the attack would come at Pearl Harbor.
What is not subject to speculation, like FDR’s state of mind, are the messages U.S. military personnel intercepted. They were increasingly ominous. They pointed to war. Various commanders in the South Pacific received copies of those messages. But the military high command in Washington did not pass them on to Admiral Kimmel and General Short.
Later, during the inevitable investigations, Pearl Harbor’s commanders were treated as though they had first-hand information. They didn’t.