Japanese military attache messages 1.jap.0 Louis J. Sheehan, Esquire






For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 (8-part set; sold in sets only)

Stock No. 008-000-00233-9

1. Iwakuro Urges That Japan Accept an Agreement 1
2. Iwakuro Advises That Japan Hasten the Agreement 1
3. Chief of Staff Learns of Hull-Nomura Talk (May7) 1
4. Japan Must Aid Nomura with a Broad Policy 2
5. Report to War Minister on Japanese-American Relations 2
6. Japanese Intelligence Reports from U.S. 3
7. The Japanese-Russian Neutrality Pact 3
8. Japanese-Russian Commercial Relations 3
9. The Japanese Establish Contacts with Axis Aviation 4
10. Japanese Seek German Manufacturing Rights 4
11. Japanese Seek Italian Manufacturing Rights 4
12. The Yamashita “Tour” 5
13. The Japanese Seek Intelligence about Russia 5
14. Japanese Intelligence Reports from Axis Nations 5
15. Japanese Intelligence Reports from Middle East 6
16. Japanese Relations with Thailand 6
17. Miscellaneous Messages 6
a. The Hull-Nomura Conversations 8
b. Japanese Activities Throughout the World 11
c. Additional Messages Found in 1977 37
1. The “Winds” Code 51
2. The “Stop” Code 55


This volume contains 1941 Japanese military attache messages which were processed by American communications intelligence in 1945 and which supplement the 1941 messages in the first four volumes. These supplementary messages are arranged in two groups, like the arrangement in the first volume of the series.

Two special studies are included regarding the “Winds” and “Stop” code messages.

Additional Japanese messages of interest have been located recently and are included in Volume V.

A summary was made, originally, of all of Parts A of all Volumes. This material is limited to the Hull-Nomura conversations.

Finally, an index is included in Volume V which covers all the Volumes.

Department of Defense 1978

Department of Defense

United States of America



PART A—THE HULL-NOMURA CONVERSATIONS (Five supplementary messages) April 16—May 11, 1941

1. Iwakuro Urges That Japan Accept an Agreement.

On April 9, 1941, the first proposals toward settling Japanese-American differences were presented to the United States State Department by “private American and Japanese individuals”. Secretary Hull and Ambassador Nomura discussed the proposals on April 14.

In a second meeting, April 16, the two men discussed further the original proposals of April 9. Secretary Hull favored the proposals with some modifications but wished also to include four principles or points (which were to prove stumbling blocks throughout the negotiations). Ambassador Nomura at once reported this discussion to Tokyo, recommending that the proposals be adopted.

The same recommendation was made by Col. Hideo Iwakuro whom Japanese Foreign Minister Matsuoka had recently appointed as an adviser to Ambassador Nomura. Sending a personal message on April 16, Iwakuro urged Major General Shinichi Tanaka in Tokyo to press for the conclusion of a Japanese-American agreement. He regarded this as a realistic measure and even compared it enthusiastically with Hitler’s Russian Pact.

2. Iwakuro Advises That Japan Hasten The Agreement.

The urgent requests of Ambassador Nomura and Col. Iwakuro that their government speedily conclude an American agreement based upon the April 9 proposals and upon Secretary Hull’s four points met a cool reception in Tokyo. The Japanese leaders awaited the return of Foreign Minister Matsuoka, who was absent on a diplomatic mission in Europe. In the course of this mission he signed the Japanese-Russian Neutrality Pact in Moscow on April 13. Although he returned to Tokyo April 22, Matsuoka delayed his reply to Washington until May 3.

Meanwhile Ambassador Nomura had sent numerous messages pressing for a settlement and was greatly embarrassed by Tokyo’s evasive delays. Col. Iwakuro, in a report of April 26 to the Chief of the Military Affairs Bureau in Tokyo, revealed that he too was annoyed by the delay, the excuse for which had been given as Matsuoka’s need for two weeks of rest. Though resigning himself to the delay, Iwakuro reported two circumstances that necessitated haste. First, popular support for aid to Britain was growing; if concrete steps in this direction were taken, they would impede a Japanese-American agreement. Second, there was increasing danger that the negotiations might become public if they were delayed, and publicity would ruin the undertaking. Ambassador Nomura, the report concluded, was exerting his utmost and had even confided to Col. Iwakuro that if the Japanese-American negotiations should fail, “he would take the honorable course”.

3. Chief of Staff Learns of Hull-Nomura Talk (May 7).

When Foreign Minister Matsuoka finally communicated with his representatives in Washington on May 3, he avoided mention of the proposals and the four points. Instead, he asked that Nomura offer, as a suggestion coming from the Ambassador, a neutrality pact similar to the one Matsuoka had just signed with Russia. The Ambassador obeyed, but on May 7 his offer was refused by Secretary Hull. The Secretary, insisting upon broad principles as the basis for the negotiations, complained that the actions and speeches of Matsuoka could not be reconciled with the principles embodied in the proposals. http://LOUIS-J-SHEEHAN.US

This conversation of May 7 was reported on that day to the Japanese Chief of Staff in an incomplete Military Attache dispatch. According to the sender, an unidentified member of the Washington Embassy (probably Iwakuro), Foreign Minister Matsuoka was not yet ready to return a formal text of the Japanese-American agreement. He had therefore instructed Ambassador Nomura to apologize for the delay, to indicate the intentions of the Axis leaders,


and to propose a neutrality pact. The sender feared that the Ambassador’s compliance with the second instruction—mention of Axis intentions—was unnecessary and perhaps harmful. He agreed with the Chief of Staff that Matsuoka’s recent public attacks on President Roosevelt and Secretary Hull were badly timed. They increased the feeling in America that the Japanese “are trying to put something over on the U.S.”. The sender concluded that “trickery and bluff” would not speed a settlement. The Ambassador himself, reporting to Tokyo on this day, said much the same thing, that this was no time for “propaganda, bluffing, and feeling out each other”.

4. Japan Must Aid Nomura with a Broad Policy.

Not until May 9 did Foreign Minister Matsuoka return to Washington a formal text of the proposed agreement. A series of discussions ensued, in the course of which much wrangling arose over the wording of the text. The author of the May 7 Attache Message sent another on the 13th., also addressed to the Chief of Staff. As he had deplored “trickery and bluff” in the former message, so now he warned against trivialities such as questions of phraseology. The Japanese Government must, he said, adopt a wide outlook to help the Ambassador obtain a favorable settlement.

5. Report to War Minister on Japanese-American Relations.

The same observer sent another dispatch on May 11 to the War Minister in Tokyo. The plan to convoy ships to Britain had hitherto been delayed, he reported, in consideration of the Japanese-American negotiations. But on May 8 the U.S. Cabinet had decided to put the plan into operation. President Roosevelt would announce the decision on Wednesday May 14. Therefore unless the negotiations were concluded before that date, the announcement, coupled with rising public opinion, would ruin them for the present. Japan’s answer must arrive by Monday, May 13, at the latest, or all hope of improving relations at this time would be lost.[a]

[a] Ambassador Nomura had already received Matsuoka’s answer but did not complete presenting it to Secretary Hull until May 12. Previously Nomura had similarly warned Matsuoka of rising opposition and urged speed.




6. Japanese Intelligence Reports from U.S.

On April 4 a circular Attache dispatch was sent from Tokyo to Washington (other addressees were England and countries of South Eastern Asia). The head of the General Affairs Department in Tokyo requested intelligence upon two points: (1) the effect of Japanese aggressions in South China upon the commerce of third powers (i.e., nations other than those of the Axis) and (2) any change in their attitude toward China. Apparently no intercept was ever made of a dispatch replying to this request.  http://LOUIS-J-SHEEHAN.US

On July 24 an unnamed official in the Washington Embassy reported plans to strengthen the Japanese intelligence network in America. Japanese-American relations were growing worse (the Japanese had invaded French Indo-China late in July). The official feared that the activities of Japanese personnel might be restricted and that their evacuation might be prohibited. He asked that a total of six observers remain in the United States (Cols. Iwakuro and Shinjo and four others). He asked that those of the six who did not possess diplomatic privileges be appointed as Aides, so that they might perform intelligence services with immunity.

On December 1 the same Japanese official in the Washington Embassy described to the Vice Chief of the General Staff in Tokyo current opinions on possible American strategy in the approaching conflict with Japan. First, cooperating with the British, Chinese, Dutch and Russians, America would blockade Japan, destroying her communications (shipping) with air power. She would then build up her military forces for a decisive blow, which, the observer thought, could not possibly come before the end of 1942. In order to employ air power against Japanese communications, she would seek bases in Australia, India, China, and would advance bases along the Aleutians even into Siberia, besides utilizing her own islands in the South Pacific together with the Philippines and Guam. Hoping that the Japanese fleet might early be drawn into a decisive battle, America felt a decision might come sooner than expected. In any case she was not worried lest the war last long. She would heavily reinforce the Philippines, the Dutch East Indies, and the Malay States in order to hold them. Being certain of victory, she would not be greatly concerned when the fighting started.

7. The Japanese-Russian Neutrality Pact.

Japanese Foreign Minister Matsuoka visited Moscow after his tour of the Axis nations. There, on April 8, he told Laurence Steinhardt, U.S. Ambassador to Russia, that the Tripartite Pact was intended to restrict the war and prevent American participation. Germany would not attack America, he added, neither would there be war talk in Tokyo if President Roosevelt would ask Chiang Kai-shek to make peace with Japan. On April 13 Matsuoka signed the Japanese-Russian Neutrality Pact.

On April 14 Tokyo released a circular Attache dispatch explaining that negotiations leading toward the pact had been pressed since early in 1940 by Ambassador Togo and, after his departure from Moscow in September, by his successor, Ambassador Tatekawa. Russian demands had delayed the conclusion of the pact until Matsuoka arrived in Moscow. The neutrality Pact, essentially a non-aggression agreement, was expected to lead to fishing and commercial treaties between the two countries.

8. Japanese-Russian Commercial Relations.

After signing the Neutrality Pact with Russia, Japan sought to improve trade relations. A secret trade agreement which had already been made in March 1941 was unsatisfactory. Japan particularly desired unimpeded exchange of goods with Germany by way of Russian railroads. But in May Russia prohibited the transit of machine tools adapted for the pro-


duction of military equipment. However, the Japanese hoped to evade the prohibition. On June 5 a message from the Military Affairs Bureau in Tokyo informed a Japanese official in Berlin that the Russians would consider permitting the passage of machine tools, ordnance, and possibly airplanes if the Japanese would accept a secret verbal arrangement rather than a documented agreement.[a]

9. The Japanese Establish Contacts with Axis Aviation.

The Japanese strove for closer contacts with Axis nations for the exchange of information and for the acquisition of manufacturing plans.

A dispatch from Tokyo on May 12 informed the Berlin Embassy that an Army Air Attache had been appointed to work under the Japanese Army Attache in Berlin. Another dispatch addressed to Rome on May 24 stated that the War Office in Tokyo was exchanging foreign air intelligence each week with Italy.

10. Japanese Seek German Manufacturing Rights.

Considerable exchange of military and technical personnel between Japan and Germany met with irksome negotiations in the matter of visas. Against the resulting delay the Japanese Embassy in Berlin protested to the War Ministry in Tokyo on April 11, fearing that much time would be lost in future exchanges. These exchanges would be frequent, the dispatch added.

Throughout these months the Japanese strove to obtain designs and samples of German military equipment and products. They desired certain IG (I.G. Farben) patents in return for exports to Germany of tungsten and molybdenum. They sought to purchase certain manufacturing rights and to obtain the assistance of German technicians to build factories. They were interested also in German airplane equipment and in German tanks.

Early in May 1941 Japanese military representative Yoshida and technical expert Kinoshita left Tokyo for Berlin to purchase IG patented processes and fuel equipment. Early in June Yoshida was in Italy studying the synthetic oil industry there. A month later another official, Col. Otani, was negotiating in Berlin for certain manufacturing rights, while the War Office in Tokyo was informed that representatives of Junkers would be sent to Japan and contacts would be established between Junkers and the Manchurian Airplane Co.

The Japanese were also purchasing samples of German teletype machines and ultra short wave electrical apparatus, samples of German armor plate, considerable quantities of optical glass, and machines for the manufacture of cog wheels.

On July 19, according to an incomplete dispatch form Berlin dated July 22, Col. Otani and Major Yoshida began formal negotiations (apparently to secure manufacturing rights) with officials of the German Economic Ministry.

11. The Japanese Seek Italian Manufacturing Rights.

Italian manufacturing rights were also sought by the Japanese. In particular, the rights to the Italian 21 (210?) howitzer were requested, and were granted through the Italian War Department, according to a dispatch of May 1 sent from Rome to the Vice Minister of War in Tokyo. However, complications seem to have retarded the actual transfer of the rights, according to a second dispatch sent from Rome May 14. A reply from Tokyo dated June 6 requested, in addition to the plans of the howitzer, a quantity of its ammunition as a sample and the right to manufacture the powder. But apparently still more complications arose, for a dispatch to the War Ministry from Rome dated November 26 revealed that the purchase of rights to this artillery piece had not yet been completed.

[a] An extensive trade agreement was signed, however, on June 9.



12. The Yamashita “Tour”.

Lt. Gen. Tetsujo Yamashita toured Europe in May and June of 1941 to observe the progress of the war and particularly to promote Japanese trade with the Axis nations in war materials and manufacturing plans. The second part of dispatch from Berlin to Tokyo dated May 15 names the German officials conducting Yamashita’s party. Goering, Brauchitsch, and Keitel were among them.

A later dispatch from Berlin to Moscow, dated May 22, revealed that Yamashita would also “tour” Italy and finally Russia, where the Japanese hoped to interview the Russian Army Minister, the Chief of Staff, and the Chief of Air Headquarters. Evidently Yamashita’s efforts were highly regarded in Tokyo, for a dispatch to Rome dated June 6 stated that an appointment to the Supreme War Council was being considered for him.

However, the Lieutenant General fell into trouble in Russia, where he arrived shortly before the German attack on June 22. A garbled message, Moscow to Tokyo June 23, mentions Yamashita, whom the Russians, it seems from a later dispatch (Tokyo to Moscow June 28), had forcibly detained for a time.

Following the industrial liaison established by Yamashita, a dispatch from Berlin to Tokyo on July 23, relayed to the members of his “tour” information on one of the latest German bombers.

13. The Japanese Seek Intelligence About Russia.

Both before and after the Germans turned against Russia on June 22, 1941, Tokyo was extremely interested in Russian strength, equipment and tactics. Scandinavian countries, particularly Finland, served as observation posts. An incomplete dispatch from Helsinki dated May 26 estimated Russian strength and discredited the rumors of impending war between Germany and Russia. Another incomplete message sent from Stockholm on May 30 and addressed to the Vice Chief of the General Staff in Tokyo gave information on Russian tactics.

Finnish sources provided much data and requested that the Japanese respond with reports on Russian activities in the Far East. One such report Tokyo sent September 26, not to Finland but to Istanbul, Turkey. Tokyo reported that the Soviet Far Eastern Army had completed mobilization about August 10 and that the army was estimated to contain about one million men, but that up to September 10 the equivalent of eight divisions had been diverted to European Russia.

Japanese observers in Helsinki reported on August 6 that the Russians were increasing the use of trench mortars. A two-part report of August 15 described new Russian automatic weapons. Another dispatch from Helsinki on August 24 described Russian airplanes. Russian forces were exceedingly weak and were declining further, according to the report, September 13, of a Japanese attache in Hungary. A message from Helsinki dated October 10 listed captured Russian equipment which was being forwarded to Tokyo.

14. Japanese Intelligence Reports from Axis Nations.

A number of varied intelligence reports involved Japanese relations with the Axis nations of Europe. The Germans requested in a dispatch of May 8 that the Japanese report to them data on British food supplies and on the extent of rationing, also data on the effect produced by air raids upon British production.

On May 12 a Japanese in Berlin reported to Tokyo the rumored military strength of Germany, 9 to 9 1/2 million men in 270 to 275 divisions and 35,000 planes. Compare this with a report of June 3 estimating 10 to 12 million men and 60 to 65 thousand planes.  Louis J. Sheehan, Esquire

Berlin requested information on May 24 from the Japanese Army commander in Hsinking on the activities of a Ukrainian Nationalist leader who had been sent from Berlin to Harbin, Manchuria.  Louis J. Sheehan, Esquire

On May 25 a Japanese observer in Rome informed Tokyo of the German air attack on Crete. Other Japanese diplomatic messages describing this event had been read in 1941.  http://LOUIS-J-SHEEHAN.US


On May 26 a Japanese agent in Helsinki noted from “intercepted wireless messages” that thirty submarines had been sent from the Baltic area to the Black Sea.

A Japanese observer in Sweden reported to Tokyo on June 11 that the Germans were setting up an agency to gather Russian intelligence. The work was centered in Konigsberg, Latvia, under the leadership of a Latvian named Alps. Konigsberg was also the location of the German Supreme Command at that time, according to a Japanese spy report sent from Rome June 20.

A report sent from Rome to Tokyo on May 8 stated that Italy had decided to aid Iraq with four of five squadrons of airplanes.

15. Japanese Intelligence Reports from Middle East.

The Japanese watched the Middle East, Iran in particular. On September 14 an official in Teheran gave Tokyo information about a Mohammedan leader. On September 22 the same official reported to Rome the size and activities of the Russian and British armies invading Iran.

16. Japanese Relations with Thailand.

While Tokyo was pressing French Indo-China and Thailand to accept Japanese influences, the British and Americans were countering Japanese pressure. A Japanese message from Bangkok dated May 3 reported the contents of an American telegram to Crosby, the British Minister in Bangkok. The telegram stated that the Governor General of French Indo-China was en route to the Philippines to take over a consignment of American munitions.

The Japanese were active in cryptanalysis. On May 17 Tokyo notified Bangkok that it was sending Major Aoyama, an army cryptanalyst, accompanied by several assistants, to intercept and decrypt British and American codes in the South Seas area.[a]

An intelligence report of May 22 from Bangkok informed Tokyo that small forces of British, Indian, and Chinese troops were stationed in Burma.

A later dispatch, July 26, from Tokyo instructed Bangkok to report on the condition of the railroads in Thailand. A few days later, after the Japanese aggression in French Indo-China, Bangkok reported the reaction of the Thaiese and quoted the policy announced by Thaiese leaders July 20, a policy of friendliness, non-intervention, and business as usual. But by November, while Japanese agents reported detailed information on Thaiese airfields and highways, Thaiese friendliness had evidently declined, according to a message from Bangkok dated November 12.

17. Miscellaneous Messages.

On April 21, 1941, a Japanese official in Budapest sent a report to the Vice Chief of the General Staff in Tokyo discussing the dismemberment of Yugoslavia. Hungary was demanding the return of several areas and in particular the Banat district.

Mexico served as a convenient post for observation and espionage in the Americas. An undated dispatch from a Japanese official in Washington informed the Mexican office that, as a result of the Japanese-American negotiations, the code clerks in the Washington Embassy were overwhelmed with messages. The Mexican office was therefore requested to transmit in code the outline only of matters concerning the Washington Embassy.

A dispatch from Mexico to Berlin dated April 28 stated that on the previous day a certain person had sailed from that country. His last name had been garbled in this transmission, but a second message from Mexico dated May 1 and addressed to Tokyo identified the man as Karl Pekowski, a German espionage agent, who had sailed with some fifty other Germans from Acapulco on the Heiyo Maru.

[a] By October Aoyama was busy in Bangkok working with Japanese naval cryptanalysts upon codes used in Burma.



On June 5 a dispatch from Hsinking to Moscow dealt with border troubles between Japan and Russia. The border between Manchuria and Mongolia had been in dispute. After the Neutrality Pact of April 13, 1941, negotiations began for a settlement. According to the June 5 dispatch the Japanese and Russian representatives, Miyakawa and Tsalapkin (who had met previously to settle matters of fishing rights), had conferred on May 26 regarding the border problem. The problem was settled by June 15 according to a message of that date.

As Japanese-American relations deteriorated, the flow of Japanese returning home increased. A dispatch from a Japanese official in Rio de Janeiro dated September 6 gave the schedules of two ships, the Noto Maru and the Toa Maru, sailing from South America to Japan in the autumn of 1941.

A dispatch from Bucharest to the Vice Chief of the General Staff in Tokyo September 9 pressed a Romanian request for raw rubber.

On December 8 a Japanese attache in Hungary addressed a dispatch to the Chief of Staff. The attache informed him that the Hungarian government and the people were sure of a Japanese victory—a faith which, he added, “is a great boost to our spiritual morale”.



a. Hull-Nomura Conversations. (supplementary messages)

April 16—May 11

No. 1

FROM: Washington (UAWRK)
April 16, 1941

TO: Tokyo (Winter (Head, General Affairs))

Personal message from IWAKURO to Major General TANAKA SHINICHI: I feel the matter reported by the Attache to the Minister and Chief of staff is a realistic measure for the Empire to take, like HITLER’S German-Russian accord. Since my arrival at my post on 2 April I’ve been working literally without a moment’s rest to rush this plan to completion, and I feel that it’s my baby. Please get (the agreement) concluded immediately and as far as possible without modification (The way I’ve managed it, an easy “out” is left open for Japan.).

Trans. 6-3-45

No. 2

FROM: Washington (UAWRK)
April 26, 1941

TO: Tokyo (RIKUGUNSHO FUKKAN (War Office. Sen Adjutant.))

4 Parts complete.

Part 1—Personal wire from Col. IWAKURO to the Chief of the Military Affairs Bureau.

According to a wire which Minister WAKASUGI received today from the Vice-Minister of Foreign Affairs, at least two more weeks will be required before instructions can be sent on the matter in hand, because of the Foreign Minister’s need for rest.

We realize that before deciding on an affair of this importance, very cautious study and all sorts of preliminary moves are necessary, and that there is something to be said for the policy of getting your man flustered with impatience so that he’ll do something rash which may redound to your benefit. So, we have resigned ourselves to some delay. But please observe these facts about the immediate situation here:

Part 2 (a) Popular anticipation of increased aid to England, of U.S. entry into the war and of a Japanese-American War, has not diminished in the least, despite the public’s desire to avoid war. On the contrary, serious consideration is being given to the formulation of concrete measures for increasing aid to England. Should this trend develop rapidly and these measures carried out in the near future, we should have to postpone the matter in hand indefinitely, because the general situation would be such as to preclude its consideration.

(b) The Americans are handling this matter with the greatest secrecy. Only the President, the Secretary of State, the Secretaries (? of War and of the Navy?) and 2 others are permitted to have anything to do with it. (Part 3) I have frequently been warned that if this affair were made public the situation would become hopeless, and, of course, the longer the delay the greater the danger of that happening.

Because of these two points, all of us here who are concerned with this matter earnestly desire that the instructions be sent as soon as possible. Therefore we request you to do what you can to speed up the Government people.

Incidentally, all I know about the Army’s viewpoint on this matter is what I learned indirectly from a recent Navy wire. (?I?) have been ordered to assist the Ambassador, direct



intelligence activities and certain inside moves, and interview Cabinet Ministers and other officials secretly. (Part 4) If you want me to direct my activities in any specific direction, please let me know about it.

The Ambassador has a strong sense of responsibility about this matter, and never slackens his efforts, day or night. He has told me that if the affair ends in failure he will take the honorable course.

(What I say about the Ambassador’s statement may create some misunderstanding if noised about, so please keep it to yourself.)  Louis J. Sheehan, Esquire

Trans. 9-1-45


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