Pearl Harbor: Warning And Decision

Roberta Wohlstetter’s Pearl Harbor: Warning and Decision is a seminal study of the series of intelligence failures that precipitated the Japanese bombing of Pearl Harbor in 1941. The book, published in 1962, investigates the warnings the US intelligence community received prior to the attack and offers an answer to the question: was Pearl Harbor preventable? Wohlstetter’s thorough research and keen analysis cemented her legacy as one of America’s most significant military historians.

Wohlstetter sifts through the information surrounding the Pearl Harbor attack to present a clear, objective picture of what happened, which officials knew what, and when they knew it. Wohlstetter’s research is based on the comprehensive thirty-nine-volume report from the Joint Congressional Committee on the Investigation of the Pearl Harbor attack, but she also does her own research into the intelligence reports and processes circulating before the attack.

Her central argument is that the Pearl Harbor bombing was the result of multiple intelligence failures. The U.S. received many, many warnings that Japan planned an attack upon US soil, yet the eventual bombing caught them by surprise. American intelligence could and did read top-secret Japanese messages written in code. The government was able to predict and prepare Japanese diplomacy and military deployments in the years leading up to WWII but failed to recognize the danger looming.



Wohlstetter identifies a number of the intelligence issues that clouded a prediction of what was to come. Last-minute warning signals in the final hours of the attack depended on fast reactions and the speed of technical communications devices. But the Army and Navy, jointly responsible for defending Pearl Harbor, were rivals. Wohlstetter describes the Navy as “jealous” of the Army flying over the water, which the Navy considered its domain. Flying was necessary for the Army to access different parts of the Hawaiian Islands. Poor communication and disagreements over who would be responsible for which types of reconnaissance led to gaps in information and poorly-organized patrols. On the morning of December 7, 1941, the line of communication to Hawaiian Air Force Headquarters was not functioning, and no Army aircraft flew overhead.

Other inter-service rivalries were significant as well: between the departments of Naval War Plans and Naval Intelligence, a military prejudice against intellectualism that made it difficult for intelligence experts to communicate their concerns, and a lack of proper funding for intelligence departments prior to entering WWII. The counties already fighting the war, including England, Germany, and Japan, allocated much higher budgets for their intelligence departments.

Bureaucracy and inter-office politics form part of the picture: petty squabbles and one-upmanship made it difficult for departments to exchange information effectively. That inefficacy led to unprecedented disaster and our entry into a global war. No single agency had all the warning signs. Only by working together could US intelligence have assembled the puzzle of the Japanese threat to America. And they didn’t—wouldn’t—do that.



Rivalry and mutual suspicion were far from the only problems. The decision-makers in Washington had ample information on Japan, but they did not have the complete list of possible targets of an attack. The lists just prior to the attack didn’t include Pearl Harbor. Nor did these decision-makers know the date or the hour; they underestimated Japanese military capabilities as well as their willingness to accept risk in the attack. That missing information turned out to be crucial.

Wohlstetter identifies the ultimate intelligence breakdown, however, not as a lack of information, but too much of it. She notes that it is easier to separate signal from noise after the fact. And before Pearl Harbor, US intelligence was flooded with “noise” on the global stage. The signals that would have foreshadowed the Pearl Harbor attack were buried beneath the signals of what was happening or going to happen in Europe. The intelligence community was overwhelmed. It was only after the event that those signs became clear.

Wohlstetter offers examples of what she calls “the very human tendency to pay attention to signals that support current expectations.” No one believed the Japanese would dare attack the U.S. unprovoked and without a formal declaration of war. Besides, there had been previous false alarms, making new ones easy to dismiss as more of the same. Japan, for its part, worked hard to conceal its plan, concocting elaborate deceptions to mislead US intelligence.



Ultimately, Wohlstetter argues that the intelligence failures were not preventable, because the signals leading to Pearl Harbor only became clear after the attack. She warns that despite our intelligence community’s technological advances, a surprise attacker would hold the advantage over us. She concludes that we must learn to be comfortable with uncertainty and “our plans must work without it.”

Pearl Harbor drew immediate praise for its scholarship and insights. In 1985, Ronald Reagan awarded Wohlstetter the Presidential Medal of Freedom for her work in analyzing intelligence breakdowns and the problem of terrorism. Wohlstetter's final warning took on new significance after the terrorist attacks of September 11, 2001, and her work was repeatedly referenced in discussing the intelligence failures that led to this new surprise attack on American soil. Then-Secretary of Defense Donald Rumsfeld made the book required reading for his aides. Wohlstetter passed away in 2007, but her work continues to resonate in the intelligence community today.