The attack on Pearl Harbor on December 7, 1941 raises some fundamental questions regarding American Intelligence at that time. The Intelligence system was sufficiently developed by 1941, with the breaking of the Japanese encoding device which is referred to as Purple, and an abundance of broken codes and signals received during the few weeks leading up to Pearl, which should have served as a serious warning to Intelligence that an attack was about to take place. Why is it then that Intelligence failed to recognise the signs and dismissed them as irrelevant?
There are several explanations for this, the first being the largely discussed conspiracy theory, which claims that President Roosevelt withheld vital information from responsible officers, thus keeping the Pacific Fleet in Hawaii open for attack, with the intention of U. S. involvement in the European War. Roosevelt knew it would be impossible to obtain support for war from Congress, and it was obvious that Germany had no intention of declaring war on America. His only alternative was war with Japan, which in turn would constitute a war with Nazi Germany.
The attack could be provoked by increasing hostilities with Japan. Roosevelt provided continued financial and military aid to China, Britain, and the Netherlands, alongside a freezing of Japanese assets and trade in July of 1941, only a few months before the surprise attack. Naval advisors had stated it was not advisable to retain the Pacific Fleet in Hawaii, but President Roosevelt objected to their advice, proclaiming it was necessary to keep the Fleet at their present position to restrict Japanese aggressions in the Far East. However, as Roosevelt was well aware, the hard truth was that the Fleet in Hawaii did not contain adequate power necessary to influence Japanese actions as a Fleet in the Far East would have done. It was obvious that the Pacific Fleet in Hawaii would need a considerable amount of increased strength to protect itself under attack, let alone have any influence over actions in the Far East. Instead of increasing its strength, Roosevelt authorised decisions to weaken the Pacific Fleet in Hawaii, including the removal of three battleships, an aircraft carrier, and several cruisers amongst other essential materials.
The alliance between Japan and Germany provided Roosevelt with an opportunity to involve the U. S. in the war without having to declare war himself and without having to gain consent from Congress or the public. He therefore followed an unrealistic foreign policy toward Japan in order to tempt Japan into an attack, an attack to which he had so kindly guaranteed them a success. An act of aggression on Pearl Harbor for instance, would result in much greater success than an attack against a Fleet based on the American West Coast. The measures taken in March of 1941 to reduce the strength of the Fleet at Pearl only provided the Japanese with more incentives.
Further evidence supporting the conspiracy theory lies within information received from decodes and the termination of the Washington Conference in November of 1941. The Japanese had made it clear to Roosevelt that this termination would lead to war with the United States and Great Britain. Roosevelt was also aware of Japan’s military history, and their reputation of entering a war with a surprise attack. Shocking evidence of messages received by Intelligence warning of an attack on Pearl Harbor, further support the conspiracy theory.
The messages were intentionally kept from responsible officers of the Pacific Fleet at Hawaii in order to avoid them from taking action to decrease the effect of the attack. As early as September, messages were received on a daily basis that should have been passed on for further analysis. Roosevelt knew of these messages, enriched with such details as the expected day and time of the attack. He knew from the decodes that the Japanese were preparing to attack on a Sunday, early in the morning, and that the possibility of the attack taking place on December 7th was close to certain. This information was knowledge to him 21 hours prior to the attack, however no effort was made to deliver this information to the responsible officers Admiral Kimmel or General Short at Hawaii.
It is in fact believed that Roosevelt directed General Marshall and Admiral Stark not to pass on messages to the Hawaiian Commanders before noon on Sunday, December 7th. Admiral Stark refused to pass on the Declaration of War messages, against the advice of his assistants, when he arrived at his office on the morning of the attack. This was very unusual behaviour for a Naval Officer to withhold such important information informing of a Declaration of War, leading to the assumption that Admiral Stark was under strict orders from the President to withhold this information.
Internationalists such as Thomas Bailey and Robert Daller believe that Roosevelt was justified in assuming that involvement in the war was inevitable. He had a reputation for being very manipulative and economical with the truth. They argue that although he tried to warn the public of the closeness of war, he deliberately mislead them by withholding Intelligence information for their own good, so that they would convert from isolationism to internationalism by force through the shock of a surprise attack with immense results.
Apart from the conspiracy theory there were other factors that played a vital role in the failure of Intelligence. American Intelligence up to the time of the attack on Pearl was highly effective and quite capable of reading and analysing Japanese codes and signals. The Japanese diplomatic codes had been broken, which enabled Intelligence to receive important information from communications between Tokyo and major Japanese Embassies around the world. There was no shortage of information, making it possible for Intelligence to paint an accurate picture of their enemy and estimate their next moves with such great detail that they could even pinpoint Japanese Fleets on their naval maps.
Despite great intelligence, there were deficiencies in the system. As interaction between the Japanese and American governments intensified during 1941, it was of great importance for Intelligence to be able to predict Japanese moves in response to their own governmental moves. This proved to be of some difficulty, as military leaders and Intelligence officers were more frequently surprised by moves of their own White House than by those of the Japanese government. How is it that Intelligence could better predict Japanese moves than those of their own country? The problem with which the White House and the State Department had to cope, was a difficulty in estimating their own military vulnerability. Therefore, it proves unrealistic to expect Intelligence to be able to predict Japanese moves when they were not even capable of predicting moves within their own government.
Although all sources of information were available to political and military leaders, it was not possible, considering the huge amount of information received, for one department to have all the information at any given time. Information would be passed from one department to the other, but as with a big company containing many different departments, it was practically impossible to retain all the information in one place. This was due to several different reason, the most influential being the fact that there was simply such an abundance of information, but also the fact that decodes and signals were often held up due to technical and procedural delays, amongst other barriers.
Due to the huge amount of information received from Magic, the best secret source of Intelligence at this time, it is easy to question the lack of preparation at Pearl Harbor after the attack. However, the signals were pointing in all different directions, making it impossible to distinguish the relevant ones from the irrelevant ones. Various signals pointed at Japanese preparation for an attack on Soviet Russia and the Far East. The signals led Intelligence to believe it was less likely that Japan would attack America immediately, but were more likely to pursue an act of aggression against other American targets such as Guam or the Philippines. Therefore it is fair to conclude that Intelligence did not fail due to lack of information from decodes and signals, but rather due to an abundance of irrelevant messages and conflicting meanings. These conflicting meanings along with the apparently sincere statements from Ambassador Nomura regarding diplomatic negotiations caused much confusion about Japan’s true intentions.
American Intelligence suffered two further setbacks shortly before the attack on Pearl. During this time it was difficult to establish the exact location of Japanese carriers, a problem that was intensified by two changes in Japanese call signs. These code changes took place at a vital time before the attack, one in November and the second in December. This had a drastic effect on the speed of radio traffic analysis and caused disagreements within the departments over the location of Japanese carriers. The Japanese code changes did raise suspicion but judging by past experiences it was believed there was no immediate danger of an attack, as this Japanese radio silence indicated that Japanese carriers were located near their homeland where they could still communicate with each other. The Japanese followed strict secrecy within their own security system. They took great care in keeping knowledge of the planned attack on Pearl down to a selected few, and sent false signals into the American Intelligence System, leading American officials to believe Japanese ships were near the homeland. Japans effort to keep relevant information quiet further confused American Intelligence and pointed them in the wrong direction.
American Intelligence faced several problems within their own security system also. They were faced with the problem of keeping vital information from being intercepted by Japan, yet also being able to distribute it efficiently to each other. As a result, not all signals were passed on, and responsible officers often did not know who had seen which information and what their analysis was upon reading the messages. Their assumptions and the reduction in recipients of messages within Intelligence deeply damaged its efficiency.
American Intelligence also had to cope with the slowness of their system. Messages were not passed on with great urgency and when passed on where often not translated or analysed until quite some time after. An incident which best shows what slow and ineffective methods American intelligence operated under at this time is the ” 1: 00 p. m. message” received on the day of the attack. Admiral Stark did not think that the ” 1: 00 p. m. message” received on December 7th held any relevance to an attack on Pearl Harbor. Investigations after the attack, it was concluded that had this message been handled with urgency, Admiral Kimmel might have received it in time to enable him to make preparations to meet the Japanese attack. The ” 1: 00 p. m. message” had been intercepted at a naval radio intercept station and was forwarded to the Navy Department where it was decrypted. It was then forwarded to the Army for translating. The message only consisted of one sentence and could have easily been translated within a few minutes, but it was not completed until hours later.
On January 24, 1941, the Secretary of War received a letter from the Secretary of the Navy, warning of increased tensions with Japan. The letter states: ” If war eventuates with Japan, it is believed easily possible that hostilities would be initiated by a surprise attack upon the fleet or the naval base at Pearl Harbor” 2. Admiral Kimmel and General Short both received copies of this letter. No further action was taken, and not until November did the Chief of Naval Operations forward the message to the commander in chief of the Pacific Fleet. However, in the message he also told the commander in chief of the Pacific Fleet of indications that Japan was about to attack Kra Isthmus, and that the Naval Department did not expect an attack on Hawaii. During this time of uncertainty and the European War in full swing, these responsible officials should have been more alert and cautious in their dealings with intelligence information. Their lack of competence and their failure in realising the true danger shall never be forgotten.
Plans to prevent an outbreak of war were joint responsibility of the military and naval authorities, and had been prepared for the defence of the Hawaiian area. These plans included Army and Navy joint defence, and expected a system of coordination and cooperation between its commanders. However, neither informed the other of actions being taken for the protection of Pearl. Prior to the attack there was no set-up for the exchange of information, decisions, and actions for joint operations. Each department assumed the other was taking appropriate actions to prepare for a possible attack, but made no inquiry to confirm these assumptions.
Magic information distribution was restricted to the Secretary of War, the Army Chief of Staff, the Director of Military Intelligence, the Secretary of Navy, the Chief of Naval Operations, the Chief of Secretary of State and the President himself. Until July of 1941 Admiral Kimmel, the Commander in Chief of the Pacific Fleet at Pearl, was provided with Magic information, but after this time he received very little information. The poor organisation of distribution between Navy and Army Intelligence staff meant that no one was certain who exactly was receiving which information. In October an Army-Navy Intelligence Committee was established to address this problem, but it did not actually meet until after the attack on Pearl.
A vital question which must be asked, is how much of the failure of Pearl were the Commanders responsible for? The Roberts Report, an investigation into the failings of Pearl after the attack, investigates this issue in detail. This report concludes that no single responsible officer was to blame for the event, and that each one carried out his or her duties accordingly. They managed to keep in touch with the international situation, consulted and cooperated with each other, issued appropriate warnings, and prepared plans for protection.
However, the plans for defence set out by commanding officers at Pearl were not put into action, and were therefore concluded as being inadequate. This left the Fleet at Hawaii unprepared for the surprise they received that fatal dawn on December 7th, 1941. ” None of these conditions was in fact inaugurated or maintained for the reason that the responsible commanders failed to consult and cooperate as to necessary action based upon the warnings and to adopt measures enjoined by the orders given them by chiefs of the Army and Navy commands in Washington.” 3 The Commanding General of the Hawaiian Department and the Commander in Chief of the Pacific Fleet, who had failed to communicate and cooperate under the given circumstances, were not found guilty of any fault due to the common opinion by the many that Japans immediate attack would be in the Far East, and that the Hawaiian area was therefore secure for the time being.
As investigations have shown, there were several factors that influenced the failings of American Intelligence to forewarn the government of the attack on Pearl Harbor. Firstly, there is the conspiracy theory, which is built around the theory that Roosevelt purposely increased tensions with Japan and withheld vital information from the Commanding Officers of the Hawaiian Fleet at Pearl regarding the attack. There were also many deficiencies in the system of American Intelligence. The system functioned slowly and inefficiently, was bombarded with an abundance of irrelevant messages that could not be recognised from the relevant ones at the time, and received several messages with conflicting meanings making it difficult to establish any certain intention of Japan. The lack in cooperation and communication within the departments further damaged the efficiency of Intelligence. It is fair to conclude that given all of these barriers to the system it was impossible to be able to predict the attack on Pearl Harbor on December 7, 1941.