in 1941, when Europe and Asia were about to fall under the offensive of the axis powers. The United States has been unable to find a reason to participate in the war, mainly because the U.S. Congress has not agreed to participate in the war. Therefore, at present, the United States needs a reason to join the World War II, which is supported by the whole United States. We all know that the United States later joined the war because Japan secretly attacked Pearl Harbor, which is equivalent to helping the United States solve a difficult problem. However, some people suspect that the United States deliberately let Japan attack Pearl Harbor. In fact, the United States already knew Japan’s plan earlier. Is that true? Conspiracy theorists of

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believe that on the eve of the Pearl Harbor incident, the high-level US officials have accurately known the time and place of the Japanese attack through deciphered intelligence.

in fact, at that time, the White House received a lot of intelligence about Japan every day. Including the contact telegram between the Japanese Foreign Ministry and the diplomatic personnel in the United States, the secret telegram sent back by the Japanese consul in Honolulu, the information monitoring the movement of Japanese warships, and the message sent back by the American diplomat from Tokyo.

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are also true or false, and even contradictory. Among them, there are not only about Pearl Harbor, but also about the Philippines, Guam and Panama – the most about the Philippines and the least about Pearl Harbor.

there are also many departments responsible for collecting and processing intelligence, including the intelligence agency of the army and Navy, the FBI, the coast guard, the Federal Communications Commission, the US embassy in Japan and other secret intelligence agencies.

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are not subordinate to each other and rarely cooperate with each other. It is impossible to integrate many one-sided and broken intelligence into effective information for US policymakers.

Roberta Wohlstetter, an American intelligence expert, studied the above situation for many years and published Pearl Harbor: warning and decision-making in 1962. Referring to the performance of US intelligence agencies in the Pearl Harbor incident, she once said:

“the signs are always clear after the event.” “We can now see what kind of disaster it foreshadowed at that time, because the disaster has happened, but before the incident, the signs are always vague and there are various contradictory understandings… In short, we failed to foresee the Pearl Harbor incident, not because of the lack of relevant information, but because there are too many irrelevant information.”

in addition, these intelligence agencies still have a short board. Although they have made great achievements in deciphering the number of secret messages, their ability to obtain effective information from secret messages is seriously insufficient. Through the “magic” system, the United States can decipher more than 95% of Japan’s diplomatic telegrams. However, due to the lack of cryptographic experts who understand Japanese, they can’t make a good analysis of the deciphered secret telegrams and inevitably miss important information.

moreover, by May 1941, Japan had discovered that the United States could decipher its foreign ministry password. Since then, Japan has stopped using this password to transmit confidential information, and the United States has lost an extremely important source of intelligence.

secondly, we can sort it out and see what the American people know about the Pearl Harbor Incident in advance.

from January to December 1941, US intelligence agencies continued to obtain information about Pearl Harbor, but they were submerged in other intelligence and did not receive due attention.

for example, on January 7, 1941, Yamamoto sent a letter to the Secretary of the Navy, initially proposing a plan to sneak attack Pearl Harbor. U.S. ambassador to Japan Geru learned this information through secret channels and quickly reported it to the State Department. Secretary of state hull immediately transferred it to the Department of the Navy and the Department of the army, but the Naval Intelligence Agency directly labeled it “another rumor”.

at the same time, Pacific Fleet Commander husband Edward Kimmel judged that Japan’s “sudden attack on Pearl Harbor (by submarine or aircraft, or both) is possible.” Frank Knox, then Secretary of the Navy, also said:

“if there is a war against Japan, Japan will choose to attack the fleet or Pearl Harbor base in Pearl Harbor as the time to start the war.”

in September 1941, a telegram from Japan asking the consul in Honolulu about the berthing of the fleet in Pearl Harbor was decoded; In October, Japan sent a telegram asking the consul in Honolulu to report the berthing position of warships twice a week. In this regard, the Naval Intelligence Agency did not pay special attention, or even forwarded it to the commander of the Pacific Fleet.

why didn’t the United States screen out these messages from a large amount of intelligence data and pay attention to them?

we must understand a simple truth: after the Pearl Harbor incident, the importance of these messages has been re recognized. But before the incident, it was a very difficult task for the US intelligence analysis department to identify the importance of these messages from tens of millions of data.

at that time, the decision-making level of the United States tended to think that Japan would not really dare to attack the United States. They judged that Japan might go north to cooperate with Germany and attack the Soviet Union together; Or go south to occupy Southeast Asia, which is more likely. At the end of November 1941, after the Japanese warships disappeared from US radio monitoring, US intelligence agencies still tended to judge that these warships were still in Japanese waters. In fact, from the perspective of the situation in the Far East occupied by the United States, the British navy is mainly responsible for the first step. For example, from the perspective of the situation in the Far East occupied by the United States, the British navy is mainly responsible for the second step The above tendentious judgment of

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is the result of comprehensive analysis of many intelligence materials, and has been proved to be reliable to some extent. Under such a premise, it is really not an easy task to identify a small number of information related to the Pearl Harbor attack from a large amount of intelligence data and realize their importanceEasy things. (similar cases are common in the history of modern warfare. For example, the national government made a serious misjudgment in the “No. 1 operation” against the Japanese army in 1944. Due to the inertia of intelligence analysis, it believed that the scale and purpose of the Japanese army’s attack were still similar to those of previous attacks, so although it received other intelligence, it failed to distinguish its importance)

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in addition, technically, the United States also believes that the Japanese Navy does not have the endurance ability to attack Pearl Harbor for a long distance, and torpedoes cannot play a combat role in the shallow waters of Pearl Harbor.

however, although they failed to fully recognize the importance of these messages, before and after the breakdown of the US Japan negotiations, the US decision-making level, who was the first, reminded Kimmel, the top commander of the US military stationed in Pearl Harbor, on several occasions to improve his combat readiness. On November 27, 1941, the Admiralty even issued a war warning to Kimmel.

unfortunately, after all, the United States underestimated Japan’s determination to put all its eggs in one basket and underestimated Japan’s technical ability – the problems of endurance and the use of torpedoes in shallow waters have been better solved, which makes it possible to sneak attacks on Pearl Harbor.

to sum up, in short: the United States failed to identify Japan’s real intention from the chaotic intelligence, which was the main reason for the hasty attack on Pearl Harbor. The so-called “Roosevelt had received information in advance, but deliberately stood still and waited for Japan to attack Pearl Harbor in order to defeat its anti war faction and obtain the reason for war against Japan” is sheer nonsense.