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Approved for Release: 2014/07/29 000622810TITLE: Japanese Army Intelligence ActivitiesAgainst the United States, 1921-45AUTHOR: Stephen C. MercadoVOLUME: 38 ISSUE: Summer YEAR: 1994Approved for Release: 2014/07/29 000622810 a tsroved for Release: 2014/07/29 000622810STUDIES ININTELLIGENCEA collection of articles on the historical, operational, doctrinal, and theoretical aspects of intelligence. ??CAl! statements of fact, opinion or analysis expressed in Studies in Intelligence are those ofthe authors. They do not necessarily reflect official positions or views of the CentralIntelligence Agency or any other US Government entity, past or present. Nothing in thecontents should be construed as asserting or implying US Government endorsement of anarticle's factual statements and interpretations.Approved for Release: 2014/07/29 000622810 Approved for Release: 2014/07/29 000622810A dismal recordJapanese Army intelligence Activities AgainstThe United States, 1921-45Stephen C. MercadoThe record of Imperial Japanese Army (IJA) intelli-gence operations against the United States from aboutthe opening of the Washington Conference in 1921until Japan's surrender in 1945 is largely one of fail-ure. Before Pearl Harbor, the Army generallyneglected a hypothetical enemy, concentrating insteadon the Soviet Union and China as its primary threats andGermany as its mockl. Military education before thewar produced few officers knowledgeable about theUnited States. Moreover, Army officers tended to dis-count intelligence on US capabilities gained before thewar.The IJA thus entered the war against the United Statesill prepared both at the level of the Army General Staff(AGS) and in the field. AGS 2nd Bureau (Intelligence)lacked a substantial analytic capability against theUnited States until late 1943. In its collection efforts,the IJA suffered from the loss of its spy network in theUnited States and its meager success in breakingencrypted US military communications. Contempt forthe United States and a general "operations first" men-tality that slighted intelligence combined with a readi-ness to believe unsubstantiated battlefield reporting andpoor coordination with the Imperial Japanese Navy(UN) to produce disasters, perhaps most spectacularly inthe Philippines, where the AGS directed a ruinousdefense of Leyte that hastened the loss of Luzon andthe subsequent invasion of Okinawa.'Neglecting a Potential AdversaryThe opening in November 1921 of the Washington Con-ference for disarmament marked a turning point for theIJA.2 The high command before then had regardedonly the Soviet Union as its hypothetical enemy. Fol-lowing the Washington Conference, however, Japan49added the United States to its list of potential adversar-ies. The IJA duly responded by designating three divi-sions for an invasion of the Philippines in the event ofhostilities.' But Army officers continued to focus theirattention on the Soviet Union, concentrating in particu-lar on turning Manchuria into a first line of defense.4Army training reflected its intelligence priorities. Mostcadets entered the IA's Military Academy from mili-tary preparatory schools, where Russian, German, andFrench were the only foreign languages taught. Only afew cadets among the minority that entered the academyfrom high schools, where English was taught, pursuedthe language as a special subject. Moreover, many IJAofficers then gained further experience in the SovietUnion and Germany by serving as military attaches ortaking study tours.' Many Japanese officers who camein contact with Germany became convinced of Germanmilitary prowess.Following Japan's entry into an undeclared war againstChina in 1937, the IJA took concrete action thatappeared to recognize the United States as a potentialproblem, offering English as one of the languages forstudents at the Nakano School for intelligence officersestablished in 1938. Even so, few of the school's gradu-ates before Pearl Harbor studied English or receivedsubsequent overseas assignments targeting the UnitedStates.Contempt for the United States contrasted sharply withthe IA's fascination with Germany. One of the keyArmy officers responsible for creating the puppet stateof Manchukuo once rejected an American officer's sug-gestion that he visit the United States on his way homefrom two years' study in Germany by saying that heApproved for Release: 2014/07/29 000622810 Approved for Release: 2014/07/29 000622810would go there only as part of an occupation force. Insuch an atmosphere, what few Army experts there wereon the United States were kept from rising to the IJA'skey positions.The preponderant influence of pro-German officers ver-sus the presence of only four or five experts on theUnited States or Great Britain holding positions higherthan section chief in the War Ministry and AGS report-edly increased the high command's "disdain" for theUnited States. The expectation that Washington wouldforsake London in the face of Hitler's juggernaut in1940 then contributed to Tokyo's decision to join Ber-lin and Rome in the Tripartite Pact that year anddeclare war against Washington the next.?Prewar Intelligence ActilLitiesThe IJA, despite its contempt for the United States as apotential foe, did conduct intelligence-gathering opera-tions on American soil. Successive Army officers in theUnited States spent years and a considerable sum ofmoney diligently building up a network of spies largelyfrom among the Japanese population. The IJA alsomonitored US diplomatic and military communica-tions. Within the IJA, the Central Special IntelligenceDepartment (CSID) conducted SIGINT activities underthe direct command of the Army chief of staff. TheCSID originated in the code research group that theIJA, IJN, Ministry of Foreign Affairs (MFA), and Com-munications Ministry established in 1921 in an annexof the MFA's telegram division. From 1936 throughDecember 1941, the CSID was able to decode or surrep-titiously read part of US State Department diplomatictraffic.'None of this intelligence activity apparently yieldedany information that caused IJA to rethink its viewstoward the United States. Indeed, Japanese militaryofficers tended to reject as astronomical even the USGovernment's official industrial production figures. Inany case, proud IJA officers tended to denigrate Amer-ica's spiritual fiber.'One key instance where good intelligence failed to swaythe IJA was the reporting of Col. Shinjo Kenkichi.Leaving Yokohama for New York City in March 1940,Shinjo settled in the New York branch of the JapaneseJapanese Armytrading company Mitsui & Co. to begin research on thewar potential of US industry. With the "valuable" coop-eration of more than 50 Japanese companies in NewYork, he produced by August an outline of his firstreport.Shinjo found that the capacity of America's defenseindustrial base was in the aggregate between 10 to 20times that of Japan. His findings were disseminated inTokyo by Maj. Gen. Iwakuro Hideo, who spent the lat-ter half of August briefing senior IJA officers. Theinformation, however, failed to change the course of IJAthinking.?Wartime Army IntelligenceWhen some 43,000 troops under Lt. Gen. HommaMasaharu launched the first large-scale Army assaulton an American position by landing on 22 December1941 north of Manila at Lingayen Gulf,'? AGS 2ndBureau lacked an intelligence staff equal to the task ofanalyzing reporting on the US military. Its lackluster6th Section, responsible for analyzing the United Statesand Great Britain, had emerged by default rather thanintention when 2nd Bureau created sections to coverother countries." Hon i Eizo, who joined 2nd Bureau inNovember 1943 after graduating from the Imperial WarCollege in December 1942, found himself assigned tothe 6th Section's America Group. Col. Sugita Ichiji,promoted after Pearl Harbor from head of the section'sAmerica Group to chief of 6th Section, belatedly beganbuilding up its analytic capability. From the end of1942 to the end of 1943, the unit grew from 18 to 65personnel, including nine staff officers and severalNakano School graduates recalled on account of thewar from their overseas insertions in the Americas andIndia.12Sugita's efforts to develop an analytic capability for thefight against the United States came too late. Hon i noteshis surprise that a 2nd Bureau section devoted solely tothe United States and Great Britain was not establisheduntil April 1942, some four months after Pearl Harbor.He describes the emergence under Sugita at the end of1943 of a substantial 6th Section as "too little, toolate." Pointing to Sugita's order that he research US50Approved for Release: 2014/07/29 000622810 Japanese Armpproved for Release: 2014/07/29 000622810,military tactics, Hon reflects that the Army should haveconducted such a survey and incorporated the resultsinto its planning in the 1920s.Hon i also quotes approvingly a postwar reflection byhis immediate superior as chief of the 6th Section'sAmerica Group that the Army High Command did notrefocus its education, training, intelligence gathering,and research from the Soviet Union to the United Statesuntil late 1943, when the US counteroffensive hadalready gained momentum. Second Bureau's focus onthe Soviet Union to the neglect of the Pacific resultedin the deaths of hundreds of thousands of soldiers,according to Hori.13Far into the conflict, many AGS officers continued toreflect the Army High Command's longstanding failureto take the United States seriously. Hon heard fellowstaff officers as lale as November 1943 dismissing suc-cessful US invasions of smaller islands by predictingthat the US military's lack of peacetime training abovethe regimental level and the Japanese Army's "incompa-rable" fighting spirit would result in disaster for USforces coming ashore against large-scale IJA forces.Hon i also recounts the visit to the War College of a 2ndBureau intelligence officer who spoke contemptuouslyof how, during Homma's invasion of the Philippines, aunit of 15 M-2 tanks retreated from a village near Lin-gayen Gulf toward Manila after offering only tokenresistance to a smaller Japanese force of nine tanks. Atthe War College, Hon learned only of easy victories atPearl Harbor, the Philippines, and elsewhere; there wasno mention of the Japanese reverses at Midway orGuadalcanal.' 4Other ProblemsThe IA's intelligence effort also suffered from insuffi-cient reporting from the field. The IA's loss of its spynetwork in the continental United States was devastat-ing, according to Hon. Washington's internment ofindividuals of Japanese descent on the West Coastdeprived the IJA of valuable intelligence on ship move-ments, US industrial trends, aircraft production, andother information. Hon i calls the internment a "strate-gic intelligence victory" for the United States far sur-passing Japan's "tactical victory" at Pearl Harbor.1551In addition, the IJA also suffered from its failure,despite great efforts, to break the higher US militarycodes after the United States changed the militarycodes in January 1942. This failure was in sharp con-trast to its successes against the Soviet Union andChina.Only late in the war did the codebreakers in CSID haveany success. In July 1944, Col. Onodera Makoto,Japan's military attach?n Stockholm and reputed chiefof Japanese military intelligence in Europe, obtained anM-209 mechanical encryption device. The CSID beganat once to analyze the device, succeeding in August todecode some frontline US military codes.Col. Nakano Takeshi, who had lead the study of thedevice, then went to Manila to assist Col. Kudo Katsu-hiko, chief of the Southern Army's special intelligencedivision, in preparing for the anticipated US return.Both men died outside Canton harbor when, accompa-nying the transfer of Southern Army headquarters fromManila to Saigon during the fighting for Leyte, theirship hit a mine.Nakano's loss left the CSID's US-British DecryptionResearch Group rudderless. It was not until May 1945,when two of the group's officers mobilized students ofmathematics and foreign languages, that the CSIDregained its momentum. Only at the end of the war didthe CSID manage to decrypt approximately 80 percentof the US military traffic.'6The CSID's failure until the final weeks of the war tocrack US military codes forced it to rely on traffic anal-ysis. Creating a nationwide SIGINT network and coor-dinating its activities with its Navy counterparts, theCSID conducted systematic collection and analysis ofB-29 bomber communications frequencies and callsigns. It then combined the information obtained withdirection-finding equipment to track approaching B-29formations and alert local air defense units. But prepa-rations by the United States to use its newly developedatomic bomb illustrates the limitations of the Army'sSIGINT effort. The CSID, through traffic analysis,detected in May 1945 an unconventional B-29 forma-tion and?with increasing anxiety?tracked it throughApproved for Release: 2014/07/29 000622810 Approved for Release: 2014/07/29 000622810August without divining its mission. Using its M-209device, the CSID managed to decode a message refer-ring to America's atomic bomb only on 11 August, twodays after the second atomic bomb had fallen onNagasaki.Acting on Bad IntelligenceThe IJA also blindly accepted wildly inaccurate report-ing of Japanese military engagements with the enemy.Hon i notes that reports from the Navy General Staff(NGS) of the number of US aircraft carriers reportedsunk or severely damaged in a series of engagementsduring November 1943 off Bougainville and the GilbertIslands suggested that the US Navy had lost every oneof its carriers. Based on the NGS's account, EighthArea Army Commander Gen. linamura Hitoshi orderedhis 6th Division to counterattack the 1 November USlanding at Bougainville; the operation ended in a costlyfailure. The Japanese military's negligence in devisinga system to verify the reports of Japanese pilots return-ing from battle forced Hon i and other 6th Section offic-ers to rely on CSID monitoring of foreign broadcastsfrom San Francisco and Sidney for more accurate infor-mation.' 7Second Bureau also suffered throughout the war frominsufficient coordination with its UN counterpart atIGHQ. Hon i indicates that the Army and Navy generalstaffs, while unified on paper within 1GHQ, had in real-ity been operating independently of each other since theRusso-Japanese War of 1904-05. Neither general staffwould inform the other of its reverses. Immediatelyafter joining AGS, for example, Hon i first learned of theJapanese disaster at Midway not from the NGS but fromthe German military attach?n Tokyo.'sIJA commanders, possessing an "operations first" men-tality, often conducted their operations, with little or noregard for the intelligence at hand. Colonel Sugita,chief of 2nd Bureau's 6th Section, viewed AGS'sneglect to build up his section until late 1943 as evi-dence of IGHQ's tendency to slight and ignore intelli-gence in planning operations. Hon i reveals that the AGSordered the Nanto Detachment at Buna, on Papua NewGuinea's north coast, to proceed over the nearly track-less jungle of the forbidding Owen Stanley Range toJapanese Armyattack Port Moresby. According to Hori, the real enemywas the nearly impassable terrain and lack of provisions.Only one in 10 soldiers from the detachment returnedto Buna after failing to reach Port Moresby.'9Nor did operations officers in 1st Bureau show muchregard for the intelligence officers in 2nd Bureau. InOctober 1944, for example, Hon i was ordered to fly toManila to brief his analysis of US military tactics to the14th Area Army commanders. While operations staffofficers had the use of reserved planes at nearbyTachikawa Airfield, Hon i had to take a long train ridesouth to Miyazaki Prefecture's Nyutabaru Airfield.In another case, when 6th Section's America Group puttogether its estimate in early 1945 that the United Stateswould initiate the anticipated invasion of the Japanesemain islands by landing its main force in Kyushu'sKagoshima Prefecture in the October-Novemberperiod, only the chiefs of 2nd Bureau and its 6th Sectionbriefed the estimate to 1st Bureau. The members ofHon's America Group did not feel at liberty to enterthe operations room.2?Debacle in the PhilippinesThe IJA's contempt for the United States, an "opera-tions first" mentality that precluded planning inadvance, a readiness to accept unsubstantiated reportingof enemy losses, and poor coordination with the UN ledto disaster in the Philippines. IJA commandersneglected to establish an effective intelligence networkwell in advance of General MacArthur's return. Theoverseas distribution of intelligence officers from theNakano School is indicative. Only two Nakano intelli-gence officers were serving in the Philippines as late asNovember 1942. Responding late to an acceleratingUS counteroffensive approaching the Philippines, theIJA attached a total of 98 Nakano graduates to the 14thArea Army only by December 1944, when Japan waslosing the battle for Leyte.21The IA's disdain for the United States and generalneglect of intelligence had also left the Army unable tobreak US military codes until late in the war. In the52Approved for Release: 2014/07/29 000622810 Approved for Release: 2014/07/29 000622810Japanese Armythree months that Colonel Nakano's group worked withSouthern Army cryptologists in Manila, they "com-pletely succeeded" in breaking the "strip coordinatecode" of the guerrillas. On the whole, however, itproved only a partial success that came too late. HadIJA obtained the M-209 earlier, Hon i reflects, the 14thArmy would have had a far better picture of US inten-tions regarding the Philippines.22The odd complacency of AGS staff officers regardingthe US counteroffensive also apparently slowed theirplanning for the defense of the Philippines until it wastoo late. IGHQ only began in March 1944 draftingplans for a decisive battle in the Philippines into whichthe IJA would throw nearly all of its resources on theislands against the invaders on the main island ofLuzon.The Army High Command moved to execute its planby upgrading in August the 14th Army in Manila to the14th Area Army and placing the 35th Army, which wasresponsible for Leyte, under its command. IGHQ thentransferred Lt. Gen. Yamashita Tomoyuki, called theTiger of Malaya for his rapid capture of Singapore in1942, from his command of the 1st Area Army in Man-churia to Manila to take over command of the 14th AreaArmy."But AGS staff officers, ever ready to underestimate theUnited States, threw away any chance for sustaining aconventional defense in strength in the Philippines byblindly accepting in mid-October an announcement of aresounding defeat of a US fleet off Taiwan. The NGSlater revised its tally downward but neglected to givethe new results to the IJA.24 The AGS readily acceptedthe results. "Drunk" on the reporting, IGHQ hurriedlyordered the decisive battleground shifted from Luzon toLeyte, where the Japanese now planned to contain USforces at the anticipated site of their first landing in thePhilippines. The result, in Hon's words, was a "his-toric blunder of a handful of strategists" in IGHQ thatpushed Japan down a steep slope to defeat.25Hon i himself witnessed the disaster unfold. Arriving atNyutabaru Airfield on 12 October on his way to Manilato brief commanders there on US military tactics, hewatched in shock as officers simply tallied on a largeboard the unsubstantiated claims of pilots returning53from the battle. He cabled the chief of AGS 2nd Bureauthat the reporting was unreliable, but his warning wentunheeded.26Arriving in Manila on 15 October, Hori learned that thevarious staff officers had entirely accepted IGHQ'sreport of a resounding victory. Hon i briefed LieutenantGeneral Yamashita on 18 October, explaining how erro-neous UN reporting in 1943 had led to the failure torepel an American landing at Bougainville. Yamash-ita's staff officers, however, continued to believed thefalse report.When a scout plane from the 16th Division on Leytereported on 19 October seeing some 10 US destroyersscreening a few battleships, most of them jumped to theconclusion that the force was the survivors from theengagement off Taiwan taking shelter in Leyte Gulffrom a storm. Hon i countered that frequent US land-ings in bad weather in the past and the occupation twodays earlier of a small island off Leyte were indicatorsof an imminent US invasion. His arguments fell on deafears until the military police called to report that adowned American pilot had revealed under interrogationthat 12 US carriers were preparing to invade Leyte.27The intelligence was accepted too late. Yamashita hadalready bowed to IGHQ orders by sending the cream ofhis units to Leyte. IJA commanders in Tokyo com-pletely misread the situation by blindly accepting theUN report of victory off Taiwan. Thinking that Gen-eral MacArthur was trapped at Leyte, IGHQ even pre-pared a victory announcement for release on 3November." Yamashita, stripped of his core units,could no longer hope to fight a decisive battle nearManila. He then deployed his remaining forces for aholding action in the mountains of northern Luzon totie down MacArthur as long as possible, thereby givinghis superiors in Tokyo at least some time to prepare forthe defense of the Japanese home Islands.29If IJA leaders had permitted Yamashita to conserve hislimited forces on Luzon rather than throwing them atthe last minute into Leyte on the basis of their own prej-udices and faulty intelligence, the Tiger of MalayaApproved for Release: 2014/07/29 000622810 Approved for Release: 2014/07/29 000622810would almost certainly have exacted far higher US casu- 6.alties and pushed back considerably the timetable forthe invasion of Okinawa. A prolonged defense could 7.even had led to the atomic bombs, Soviet entry into thewar, and Tokyo's surrender without the deaths of some 8.12,000 US combatants and over 150,000 Japanese mili-tary and civilian casualties in the battle for Okinawa. 9.Notes1. This article is based on a number of Japanese andAmerican sources. The accounts of two IJA intelli-gence officers who served in 2nd Bureau are espe-cially useful. Hon i Eizo, who worked in AGS 2ndBureau's America Group and in the Philippines aschief intelligence officer to Lt. Gen. Yamashita To-moyuki, has written Daihovi Sanbo No Joho Senki(An IGHQ Staff Officer's Record of IntelligenceWarfare) (Tokyo, Bungei Shunju; 1989). HayashiSaburo, who headed 2nd Bureau's Soviet section, isthe author of Unofficial History of Army Battles inthe Pacific War. Tokyo, Iwanami Shoten; 1951. Inthis article, I have drawn on the annotated Englishversion that he and historian Alvin Coox published asKogun: The Japanese Army in the Pacific War(Quantico, VA: Marine Corps Association Press,1959). I have put Japanese personal names in theJapanese order, surname followed by given name.2. Meirion and Susie Harries, Soldiers of the Sun: TheRise and Fall of the Imperial Japanese Army. (NewYork, Random House; 1991) p. 133. The Conference'resulted in the IJA's giving up its gains in Siberia,Tsingtao, and on the Shantung Peninsula, the UNbowing to a 6:10:10 ratio regarding the United Statesand Great Britain in capital ships, and the terminationof the Anglo-Japanese Alliance.3. lwakuro, Hideo. Junbi Sareteita Himitsu Sen (Co-vert Warfare Prepared), Shukan Yomiuri, 8 Decem-ber 1956, p. 21.4. Hayashi and Coox, p. 7.Japanese ArmyHayashi and Coox, p. 7.Hori, pp. 82-84, 171, 210, 233-34.Hayashi and Coox, p. 23.lwakuro, pp. 22-23.10. Karnow, Stanley. In Our Image: America's Empirein the Philippines. (New York, Random House;1989); p. 291.Richelson, Jeffrey. Foreign Intelligence Organiza-tions. (Cambridge, Mass., Ballinger Publishing Co.,1988) p. 250, and Hon. pp. 39-43.12. Hori, pp. 13-14, 49-54, 77.13. Ibid., pp. 49-54, 78,. 134.14. Ibid., pp. 30-32, 54.15. Ibid., p. 84.16. Ibid., pp. 171-72, 210-19, 234.17. Ibid., pp. 87-93, 101, 145.18. Ibid., pp. 30-32, 87.19. Ibid., pp. 78, 98.20. Ibid., pp. 135, 223.21. Nakano Koyukai. (Society of Friends of the NakanoSchool) Rikugun Nakano Gakko (The Army NakanoSchool) , pp. 522-23.22. Hori, pp. 171-72.23. Drea, Edward. MacArthur's ULTRA: Codebreakingand the War Against Japan, 1942-1945. (Lawrence,Kansas: University of Kansas Press, 1992) pp. 159-60. Hayashi and Coox, pp. 121-22, 126-27.5. Spector, Ronald. Eagle Against the Sun: The Amer- 24. Ibid., pp. 166.ican War Against Japan. (New York, Free Press,1985) p. 38. 25. Hon pp. 156-57.54Approved for Release: 2014/07/29 000622810 Approved for Release: 2014/07/29 000622810Japanese Army26. Ibid., pp. 135-39.27. Ibid., pp. 141-44, 152-55.28. Drea, pp. 167-68.29. Hon. pp. 132, 174, 221.55Approved for Release: 2014/07/29 000622810