Rumors have swirled for years that Roosevelt knew Japan was planning an assault on Pearl Harbor and simply let it happen.
The Japanese navy attacked the US fleet at Pearl Harbor on December 7, 1941. The next day, President Franklin D. Roosevelt called it "a date that will live in infamy." Despite the country's formal neutrality, Roosevelt personally wished for the United States to join the war on England's side. He had persuaded Congress to lend money, food, ammunition, aircraft, ships, and Lend Lease to England, as well as to monitor and convoy British ships in the Atlantic. These steps, Roosevelt informed the public, were not meant to drag the United States into war, but rather to keep us out of it. While we were still technically at peace and working to resolve different disagreements, Japan's invasion provided Roosevelt with the justification he needed to approach Congress for a declaration of war.
People believed the President when he said the fleet had been attacked "suddenly and intentionally" by Japan. People only discovered after the war that FDR's administration and key military leaders had not been as astonished as they had been: the US government had known many of Japan's goals from mid-1940, when intelligence operatives decoded her highest diplomatic code. Officials in Washington had been anticipating robust Japanese action in the Pacific. Another dispute is whether or not they anticipated the attack on Pearl Harbor.
For years rumors have circulated to the effect that Roosevelt knew that Japan planned to attack Pearl Harbor—and just let it happen. By far the most detailed and credible claim to date is contained in Robert Stinnett’s book Day of Deceit: The Truth About FDR and Pearl Harbor. Stinnett is a Navy veteran of World War II who spent his life as a newspaper journalist and photographer. He argues that ample evidence was available to U.S. administration and military officials—through Japanese intercepts decoded and translated before the attack—to indicate that Japan was planning to attack Pearl Harbor. The Pearl Harbor commanders, Admiral Husband E. Kimmel and General Walter C. Short, would not have been surprised if they had been properly informed. Washington, however, chose to keep them in the dark.Stinnett describes three "conspiracies": the first, to force the Japanese to attack the United States and thus drag us into World War II; the second, to deprive the Pearl Harbor commanders of available information about Japan's intentions; and the third, an ongoing attempt to keep pre-attack information hidden from the public.
According to Stinnett, the first "plot" began in October 1940, when Japanese specialist Captain Arthur McCollum, commander of the Far Eastern Section of Naval Intelligence, wrote a memorandum. The brief outlined eight actions that may be used to persuade Japan to "perform an overt act of war." First and foremost, the US fleet's core strength should remain in Hawaii. Over the concerns of James Richardson, commander-in-chief of the US fleet, Roosevelt quickly organized this. McCollum's other proposals were also implemented during the next year.
According to Stinnett, U.S. cryptographers had deciphered not only Japan’s diplomatic code known as MAGIC, but also some of her military codes, enabling operators in U.S. monitoring stations around the Pacific to intercept and decode countless Japanese military dispatches. Significant information was received from these intercepts, Stinnett says, including the Japanese Task Force’s last-minute choice for its staging area, its destination, and its attack order. But that intelligence was purposively withheld from the Pearl Harbor commanders.
On November 23, Kimmel, as the Fleet's Commander in Chief, had authorized a hunt for Japanese forces north of Hawaii, without White House authority, and had pushed the Pacific fleet into the North Pacific. Kimmel's ships were sent back to Pearl Harbor after White House officials learned of this and worried the force might collide with the Japanese attack convoy. The Navy in Washington also directed Kimmel on November 25 to move all transpacific trade southward, leaving the north Pacific "empty" and therefore vulnerable to the arrival of the Japanese convoy, according to Stinnett.
Judging by the words and actions of Roosevelt and his advisers it is hard to believe that they were as sure as Stinnett indicates they were that the Japanese attack on Pearl Harbor, which they wanted, was imminent. For instance, at a meeting of Roosevelt’s “War Cabinet” on November 25, Secretary of War Henry Stimson remarked that “the Japanese are notorious for making an attack without warning, and the question was . . . how we should maneuver them into the position of firing the first shot without allowing too much danger to ourselves.”
Even though Stinnett's case does not sound totally compelling to me, he has gathered a significant amount of previously unknown information. Anyone interested in the events leading up to the Japanese attack, as well as the administration's subsequent attempts to deny responsibility and pin the blame on the commanders, who were not only denied vital military intelligence, but also hampered in their efforts to gather it themselves, will find his book fascinating reading.