This is the story of Japanese intelligence operations before and during World War II, and the ways policy makers and war planners used and misused the information that was collected. In his forward, Williamson Murray (Ohio State) describes the work as "a detailed examination of the bureaucratic, organizational, and cultural aspects" that rendered the "Japanese military ... in most respects dysfunctional in the field of intelligence" (vii).

Ken Kotani is a fellow of Japan's National Institute for Defense Studies (NIDS), specializing in the intelligence history of Japan and the United Kingdom, with emphasis on World War II. To write this history he faced a formidable task: the Imperial Japanese Army (IJA) and Navy (IJN) "destroyed most intelligence documents at the end of the war. In addition, intelligence officers of the IJA and IJN were unwilling to talk about their roles, as they were afraid of being punished by the victorious Allies" (1). Kitani "dug up and struggled with the fragmented primary sources" (ix), as well as examining existing literature and available British and other intelligence documents.     

Japanese intelligence has its roots in Sun Tzu's The Art of War, which Japan's early military thinkers studied. From the establishment of the IJA and the IJN in 1868, each service had its own intelligence apparatus. Their focus was tactical, "influenced by the Prussian style of limited war" (8). That served Japan well in wars with China in 1894-95 and Russia in 1904-5, but, not having participated in World War I, it failed to understand "the concept of total war" that required "total intelligence," including factors well beyond the scope of military collection and analysis (8).

In the run-up to World War II, both services collected information through methods ranging from exploitation of open source material and military attachés abroad to signals intelligence (SIGINT) and code breaking. The use of foreign agents was apparently limited and, in some cases, not greatly successful. One IJN officer wrote: "We succeeded infiltrating the U.S. government, but after the outbreak of the war the agents were obliged to move to Mexico, Argentina, and Chile.… We hired native Chinese and Australian in New Guinea, but they eventually double-crossed" (10).

By contrast, the success of the Japanese in code-breaking is most impressive. The IJA's main target was the Soviet Union, while the IJN focused on the United States and Britain. The IJN broke low-level U.S. diplomatic codes early in the 1920s, and also "part of the British diplomatic code," discovering "that the British defense of Malaya was highly vulnerable" (15). Kotani asserts that "the IJA had significant success in breaking Allied [military] codes" during the war (18), although a postwar U.S. report suggests these were "low grade…, principally weather and aircraft codes," and that the Japanese "apparently had not succeeded in reading any high-grade American or British cryptographic systems" (5).

The real threat to the Allies came from Chinese codes. The IJA broke Chinese military codes in Manchuria as early as 1928, the KMT diplomatic code in 1936, and subsequently "Chinese systems of all types" (5). A senior IJA General Staff officer wrote: "The IJA could divine the intentions of the United States and Britain through the Chinese coded cables" (20). The Allies knew this from reading the Japanese cables, and had to be very selective about information they passed to the Chinese.

IJA code-breakers who targeted the Soviet Union had trained in Poland in the 1920s. SIGINT sections in Manchuria broke the Red Army's code in 1935. During the war, IJA code-breaking operations were established in Hungary, Finland, and Poland in cooperation with the host services, while "British and US codes decrypted by the IJA were exchanged for Soviet codes decrypted by Germany" (24). The IJA's SIGINT was very extensive: "the IJA had eight SIGINT sites in Manchuria … acquiring 50,000 cables a year," but suffered severe shortages of staff and funds. Kotani observes that "Japanese SIGINT competence could have been equal to that of the United States or Britain if they had urgently increased the staff to cope with the enormous volume of traffic" (25).

The unfortunate term HUMINT, designating IJA attachés working abroad, encompasses their exchanges with local counterparts, open-source collection, and the "hiring" of agents. From 1919, the primary target of IJA HUMINT operations was again the Soviet Union, while "Soviet security centered on battling Japanese intelligence" (28). The full range of operations against the Soviets included massive watch operations along the Manchurian-Soviet border, exploitation of Russian defectors, and attempts to run Russian agents back across the border. "Manchurians, Koreans, and Mongols were also chosen as spies, but most of them tended to be Soviet agents" (36). "Operations against the Soviets were extremely laborious, 'like searching for very fine gold dust in the mud'" (32).

In the late 1930s, an attempt to improve Japanese intelligence, particularly against the Soviets, included the establishment of the Nakano school for the "rapid training" of officers who "would fight in the covert war … of espionage, propaganda, security, and plots" (31). The first class of eighteen graduated in 1939, but "HUMINT" successes against the Soviets did not increase significantly. The most reliable information came from censored open source material: the attaché in Moscow predicted the Soviet invasion of Poland by reading Soviet newspapers (40).

HUMINT collection in China was more effective. IJA attachés had been posted in major Chinese cities since the late nineteenth century and a cadre of "China hands" developed. Some, like General Kenji Doihara, "Lawrence of Manchuria," became famous. But they were "specialists," and that meant a "shortage of expertise on Chinese affairs as a whole" (43). IJA also ran counterinsurgency operations against both the KMT and the Chinese Communist Party (CCP). At the outset, the IJA had no CCP specialists, held the Eighth Route Army "in low esteem," and was "deeply shocked" when 20,000 Japanese soldiers were lost to CCP attacks in 1940 (44).

The Navy collected intelligence on the United States from 1909 on, although the section responsible had "fewer than ten staff until the attack on Pearl Harbor" (69). IJN code breakers had early successes, particularly in China, but "from the interwar period through the Pacific War the IJN made a generally poor effort in code-breaking while their own codes were cracked by the Allies" (76). The Navy had long considered the possibility of a war against Britain or the United States, and in 1937 "decided to focus SIGINT on the Hawaii area," the base of the U.S. Pacific Fleet (72). During the war, even though codes could not be broken, traffic analysis gave useful indications of the targets and timing of U.S. attacks.

Few records of Navy HUMINT operations exist, but Britain's MI5 had good files on Britons who served as IJN agents, including several Royal Navy officers who were compromised to MI5 early on. Herbert Greene, brother of novelist Graham Greene, became an IJN spy in 1933, and then told the Daily Worker. Great IJN hopes rode on ex-RAF officer, F.J Rutland, a hero of the Great War and an expert on carrier aircraft, who became an "adviser" to the IJN in 1923. He moved to California in 1934, set up front companies, and "behaved like a billionaire" (82). The FBI quickly pegged him "as in charge of Japanese intelligence works in America" (84). He was repatriated to Britain in 1941 and interned as a collaborator. Though he must have cost the IJN a great deal of money, "he seems not to have reported much genuinely useful information" (86).

Kotani believes that "in the first phase of the Pacific War, Japan was good at using tactical intelligence" (159). Pearl Harbor was the outstanding example. Once it was decided to draft a plan for an attack, an IJN officer was posted to Hawaii as a junior diplomat. He made sight-seeing trips around Oahu and reported to Tokyo details of installations, airfields, and the strength and location of the U.S. fleet. Other IJN officers booked passage on liners to explore the seaways, and collected information "from human sources in Hawaii" (137). Security was flawless. Neither the IJA nor the Ministry of Foreign Affairs was informed of the target, and few in the IJN knew the specific plan. Once the ships deployed, radio silence was total. The Americans never had a clue: "this was not American failure, but the success of Japanese security" (137). That would soon change.

"IJA and IJN information gathering was not poor, but structural flaws meant that the efforts were often wasted." The flaws comprised "the vulnerable position of the military Intelligence Departments, the lack of a central intelligence machinery, and the war planners' indifference to intelligence" (159). Causing further vulnerability were IJN operations staff--the best and brightest--who looked down on the intelligence staff and tailored their own assessments to support IJN strategic goals (160). Evidence contrary to operational staff assessments was ignored. This was not analysis, but wishful thinking. 

The lack of a coordinating body--a central intelligence organization--caused many problems as the war went on. The IJN took heavy losses at the Battle of Leyte Gulf, but announced it had sunk eleven U.S. carriers, two battleships, and three cruisers. Crediting this report, IJA planners shifted their main force from Luzon to Leyte--only to have much of it annihilated in transit by U.S. aircraft that should not have been there.

The most striking example of Japanese intelligence failure--on many levels--was the compromising of IJN operational codes prior to the battles of the Coral Sea and Midway. Though the IJA knew secrets were being leaked, its "conceit [was] that 'our codes cannot be broken'" (90):

The chief staff officer of the 1st Air fleet noted: "The major factor of the failure in the operation was the leaking of the Japanese Combined Fleet's plan on the battle of Midway to the US Navy." In the operational diary of the General Staff it was recorded that "the enemy had grasped our intentions beforehand." However, in the minds of the Navy General Staff, the major factors behind the defeat were technical issues, such as a problem in liaison between the fleets and replenishment vessels and the lack of reconnaissance…. The lack of thorough examination regarding code failures resulted in the shooting down of the plane of Admiral Yamomoto on April 18, 1943 (87-88).

And there was no help from the Army: "Although the Army SIS could break some of the US military ciphers … the Navy SIS failed to break them. The Army was superior to the Navy in code-breaking and the code-breakers of the IJA knew the vulnerability of the Navy's code. However, they did not share their knowledge of code-breaking, and the Navy was not informed of their vulnerability" (162).

"But the fundamental  problem was the Japanese decision-making process itself, which could not handle intelligence for war planning or for strategic policy" (150). Official decisions, once made, became impervious to change by "rational ideas" or by intelligence. In the prewar period, three power centers--the IJA, the IJN, and the government--each pulled in its own direction, with no one entity formulating national strategy. Before that, the Genro (the Emperor's advisers) had set Japan's grand strategy, but they had been pushed aside by the IJA. Intelligence became useful when it supported a position being negotiated within the power structure. "The war planners usually chose reports in an arbitrary and impromptu manner for their own strategic goals" (163). The IJA Chief of Staff is quoted on one such occasion: "The report is perfect and there is no room to argue. But the report is against our national policy" (151). The report was ordered burned.

Kotani convincingly describes what Professor Murray calls "not so much a failure of the intelligence organizations themselves as a massive failure of the culture and bureaucratic organization of the Japanese military from top to bottom" (viii). The book is indeed a significant contribution to the literature of intelligence and World War II, particularly for English-language readers with no access to works in Japanese. The translation, by Kotani's wife, is competent, despite a few odd word choices (for example, Japanese agents are "hired," not recruited), too many unfamiliar acronyms, and occasional imprecise phraseology.

The bibliography attests to extensive use of Japanese and British documents, but U.S. documents are limited to Office of Naval Intelligence "Records of the Oriental Desk" and a brief history of communications intelligence in the United States. There is but a single reference to the Office of Strategic Services (OSS) and none to Chinese documents. This does not diminish Kotani's accomplishment, but suggests that future explorations of U.S. and Chinese sources may add further insights into Japanese intelligence operations, perhaps like those Kotani gained from MI5 files. Nonetheless, this important work will benefit specialists and general readers and indeed anyone wanting a more complete picture of Japanese intelligence during World War II than previously available.

Alexandria, VA
bbergin99@gmail.com