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Intelligence Throughout History: The Impact of Pearl Harbor

Between the Revolutionary War and World War II, the United States lacked an established, professional,centralized intelligence organization. Up until WWII, the country didn’t see the need for it. On December 7, 1941, the need for a centralized intelligence organization was clearly demonstrated when waves of Japanese aircraft swept from a clear sky to bomb U.S. Navy ships and Army installations around Pearl Harbor.

The attack on Pearl Harbor began at roughly 7:53 that morning. At 8:05 a.m. the battleship USS Arizona erupted in a massive explosion ignited by a bomb that detonated in its forward magazines.  Minutes later, the ships lined up at Battleship Row were also bombed. Japanese attackers had achieved a stunning tactical surprise. The shock of that disaster still reverberates.


Lessons from the Past

Lessons drawn from Pearl Harbor were included in the intelligence reforms accomplished by the National Security Act in 1947, and its anniversary was even cited by Representatives as they passed the Intelligence Reform and Terrorism Prevention Act in the House on December 7, 2004.

As living memory fades, our understanding of Pearl Harbor seems likely to remain fairly well settled. Conspiracy theorists have insisted that the Japanese success was not due to careful planning and execution, but must have resulted from some form of wrongdoing on the American side.

Yet none have produced evidence to shake the basic findings of Congress' joint investigation in 1946. Congressional probers basically blamed the disaster on a lack of imagination and watchfulness on the part of the American commanders on the scene, combined with poor coordination and exchange of intelligence in Washington.

This does not mean that we know all there is to be known about what happened in 1941. There have been minor discoveries over the last generation, mainly about Japan's ability to read cables between Washington and its embassy in Tokyo, and the disclosure of the U.S. Navy's decryption (in 1945) of Japanese naval messages intercepted before the attack. These have contributed a new understanding, but have not changed the basic story.


The National Security Act of 1947

Decisionmakers in the White House and Congress drew several lessons from Pearl Harbor as they crafted the National Security Act in 1947. In the view of President Harry S. Truman, the Japanese attack might have been prevented "if there had been something like coordination of information in the government."

President Truman observed in his memoirs:

"In those days the military did not know everything the State Department knew, and the diplomats did not have access to all the Army and Navy knew."

For students of intelligence, the enduring lesson of December 7, 1941 was separating "signals" from "noise .” American commanders and intelligence officers were surprised by the Japanese attack not because they lacked clues to Tokyo's intentions and capabilities but because those clues lay unnoticed amongst volumes of unrelated or even misleading data. Pearl Harbor has quite literally become a textbook example for new intelligence analysts.


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Posted: Dec 10, 2010 12:17 PM
Last Updated: Apr 30, 2013 12:42 PM