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SINCE 1997
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Acta Historica Tallinnensia
ISSN 1736-7476 (Electronic)
ISSN 1406-2925 (Print)


This article aims to unveil the truths of the interwar Japanese intelligence activities in the Baltic States. Starting from the publication of Yuriko Onodera’s memoir ‘In the Shore of the Baltic Sea’ in 1985, the activities began to catch scholarly attentions. The activities were partially covered in some of the previous academic publications, such as a general picture of Japanese intelligence plan ‘1932’ in Kuromiya & Mamoulia (2016). However, this is the first-ever article to provide a perspective of the activities of the Japanese military attaché office in Riga.


1.        May, E. R. (ed.). Knowing One’s Enemies. Princeton University Press, New Jersey, 1986, 430.

2.        Koshiro, Y. Imperial Eclipse: Japan’s Strategic Thinking about Continental Asia before August 1945. Cornell University Press, New York, 2013, 16.

3.        May, E. R. (ed.). Knowing One’s Enemies, 430.

4.        Degras, J. Soviet Documents on Foreign Policy. Volume 2: 1925–1932. Oxford University Press, New York, 1952, 23. Kopp mentioned that the ‘Soviet-Japanese agreement is an instrument of peace’ and the ‘Soviet government has no other intention than to use it to develop economic and cultural relations between the Soviet and Japanese people’.

5.        Degras, J. Soviet Documents on Foreign Policy. Volume 2: 1925–1932, 233–235.

6.        Kuromiya, H. The mystery of Nomonhan, 1939. – The Journal of Slavic Military Studies, 2011, 24, 4, 662.

7.        Ibid., 663. Koyanagi invited his Russian language teacher and a ‘doctor’ (both were female) to a house party at his residence. There, he had a heated political debate with the teacher. Even had a brawl with and injured her slightly. According to the Polish intelligence, both women were Soviet OGPU (State Political Directorate) agents. They attempted to steal keys of Koyanagi’s personal safe, but prevented by him thus pretended to be ‘threatened’ and attempted to conceal the crime.

8.        Latvijas Valsts Vēstures Arhīvs, Rīga (LVVA) 2570-1-215, 50.

9.        The three ports were previously reported to Tokyo as good natural ports’ by Sentaro Ueda, representative of the Riga diplomat office (1923–1926), on 21st October 1923 (Shima, S. Introduction to Japanese-Latvian relations between the wars: (1) The beginning of diplomatic intercourse. – GAKUEN, 2005, 772, 95).

10.     Rahvusarhiiv, ERA.495.12.119.25. Koyanagi and Matsumoto’s personal information attached as a personal memo. Then Estonian military attaché in Warsaw was Major Ludvig-Karl Jakobsen. Jakobsen filled the position between 1924 and 1930.

11.     Feldmanis, I., Stranga, A. The Destiny of the Baltic Entente: 1934–1940. Latvian Institute of International Affairs, Riga, 1994, 13.

12.     The trip of Koyanagi and Matsumoto to the Baltic States, despite its confidentiality, was taken up by German newspaper in Latvia. The newspaper reported Koyanagi was confirmed in Kowno, Poland (Riga am Sonntag, 26 August 1928). Thus it seems that the Soviets were fully aware of their trip as well.

13.     Kawabe, T. From Ichigayadai to Ichigayadai: Memoir of the Last Vice Chief of the General Staff. Jiji Press Co., Ltd., Tokyo, 1962, 52. The Japanese Army had consecutively sent three young officers to Riga between 1924 and 1929, for the language exchange.

14.     Okabe, N. Disappeared Yalta Telegram. Shinchosha, Tokyo, 2011, 23. Makoto Onodera, the third Japanese military attaché in Riga (1936–1938), recollected in the postwar memoir that he took the Soviet information delivered by diplomatic couriers from Tokyo to the Latvian General Staff.

15.     ERA.495.12.119.30.

16.     Boyd, C. The Berlin-Tokyo axis and Japanese military initiative. – Modern Asian Studies, 1981, 15, 2, 314–315. The conference was hosted by Major General Arichika Omura, then military attaché in Germany, and managed by Lieutenant General Iwane Matsui, director of military intelligence at the Army General Staff in Tokyo. Thus, it is rational to think that the subversive plans against the Soviet Union were formally authorized by Tokyo.

17.     The Japanese decision was probably based on the success of the assassination of Pyotr Voykov, Soviet plenipotentiary representative to Poland, in 1927 by Boris Koverda, émigré White Russian. The Soviet government severely criticized the Polish government for the support to the émigré Russian organizations (Degras, J. Soviet Documents on Foreign Policy. Volume 2: 1925–1932).

18.     Rutkowska, E. The Impacts of the First Russo-Japanese War on the Bilateral Relationship between Japan and Poland in the Early 20th Century. National Institute for Defense Studies (NIDS), Tokyo, 2006, 161. Rutkowska also found Colonel Gruzien, Polish military attaché in Moscow, reported to the General Staff that the Japanese Army decided to establish a ‘base’ in Poland for gathering the Soviet information.

19.     Kuromiya, H., Mamoulia, G. Eurasian Triangle: Russia, the Caucasus and Japan, 1904–1945. De Gruyter Open, Berlin, 2016, 136.

20.     Ibid., 137: NARA, RG331, Evidentiary Document 2979.

21.     Following the instruction, from November to December 1933, Lieutenant Colonel Tsutomu Ouchi, military attaché in Riga who was a successor of Kawamata since the early 1933, visited Helsinki several times to negotiate the stationing of military attaché with the Finnish General Staff. And, on May 25th 1934, Major Seiichi Terada, the first-ever Japanese military attaché arrived to Helsinki.

22.     Sibīrijas Cīņa, 17 October 1934. The Riga correspondent mentioned the rumour that the Japanese military attaché in Warsaw had a secret meeting with the Polish counterpart. He also noted that the Japanese were actively working with Finns following the visit of ‘Akacaki’, Japanese industrial magnate, to Helsinki.

23.     Obata’s residence in Tallinn was Rüütli tänav 12, as of 1921 (Eesti välisteenistuse biograafiline leksikon 1918–1991. Eesti Välisministeerium, Tallinn, 2006, 151).

24.     Hommikuleht, 13 September 1933.

25.     Japan Centre for Asian Historical Records (JACAR), 23. Latvia. Ref.: B14090839400. (Access Date and Time: 31 January 2018 17:15 PM). Major Akio Doi of the General Staff summed up Ouchi’s reports on the issue and concluded that the change in Estonian altitude toward the Japanese Army mainly resulted from the purge of General Gustav Jonson of the General Staff who had been acknowledged as one of the most pro-Japanese (being also a hardliner against the Soviet Union) Estonian military officials. It is said that Jonson had a connection with the right-wing movement of the War of Independence veterans thus relegated after the Estonian Presidential order to prohibit members of the military forces to take part in the politics on February 27th 1934.

26.     ERA.495.12.119.27.

27.     JACAR. Exchanging small arms and pistols with the nation of “Estonia”. Ref.: C01006736600. (Access Date and Time: 1 February 2018 10:32 AM).

28.     Diena, 15 May 1993.

29.     Ibid. According to Valerija Sieceniece, it was one of music players at the hotel bar.

30.     Diena, 15 May 1993.

31.     Onodera, Y. People on the Shore of the Baltic Sea. Shinpyoron, Tokyo, 2016, 183. The name of the American diplomat is not confirmed and Nina was not registered as an official spouse of any of the diplomats in Riga, according to the official database of the U.S. Department of State. – Diena, 15 May 1993.

32.     Kawada, M. History of the Japanese Army. Volume 1. Kodansha, Tokyo, 2014, 60.

33.     Obata volunteered for the Imperial Russian Army during the First World War, and Nagata had been stationed to Germany, Sweden, and Denmark throughout early 1910s.

34.     Crozier, A. J. The Causes of the Second World War. Blackwell Publishers Ltd, Oxford, 1997, 200.

35.     Onodera, M. Generals Talk: Major General Makoto Onodera. Volume 1. Kaikosha, Tokyo, 1985, 6. In the article, Onodera addressed Nagata without using an honorific title (‘General’ etc.), merely ‘Tetsuzan Nagata’.

36.     Onodera, Y. Records of Intelligence Activities of Major General Makoto Onodera: 1935–1946. Volume 1. Yasukuni Kaiko Archive, Tokyo, 1992, 29.

37.     Okabe, N. The God of Intelligence. PHP Institute, Tokyo, 2014, 85; Okabe, N. Disappeared Yalta Telegram, 109.

38.     ERA.495.12.119.32. In the letter addressed to foreign military attaches accredited to Estonia, the 2nd department indicated their purposes as follows: 1) exchange of information, and 2) interviews with Estonian military officials.

39.      ‘Ostpakt’ refers to the ‘Eastern Pact’, characterized by a multilateral mutual-aid treaty proposed by the Soviet Union to its Eastern neighbours including the Baltic States in the mid-1930s. After the diplomatic pressure from the Soviet Union, Estonia also agreed on the Pact proposal in summer 1934 (Radice, L. The Eastern Pact, 1933–1935: A last attempt at European cooperation. – The Slavonic and East European Review, 1977, 55, 1, 51).

40.     JACAR. Part E / 2. Estonia / 7. Relations between Estonia and Soviet Union. Ref.: B02030844500. (Access Date and Time: 31 January 2018 13:40PM). The relationship between Onodera and Sakuma is shrouded in mystery, although Yuriko Onodera often mentioned him pleasantly in her memoirs, whereas Makoto Onodera never mentioned him. The United States first succeeded in decrypting the Japanese diplomatic code in 1937, thus Onodera might have been aware of the weakness of the diplomatic code and it was the biggest reason why he hesitated to share the Reek information with Sakuma immediately.

41.     Onodera, Y. Records of Intelligence Activities of Major General Makoto Onodera: 1935–1946, 30. Villem Saarsen also left a memoir titled ‘What I saw’ (See mis ma nägin), however only two paragraphs were spared for Makoto and Yuriko Onodera. There was nothing about the actual intelligence cooperation.

42.     Onodera, Y. Records of Intelligence Activities of Major General Makoto Onodera: 1935–1946, 33.

43.     Office of United States Chief of Counsel for Prosecution of Axis Criminality. Nazi Conspiracy and Aggression. Volume 1, 1946, 842.

44.     Okabe, N. Disappeared Yalta Telegram, 110–112.

45.     Kansallisarkisto (National Archives of Finland), Helsinki, 3134-M36, 17. The VALPO officer answered to Kato that the Ukrainian émigré movement in Finland is very small in its scale and not active.

46.     See pages 83–84 of this article.

47.     Onodera, Y. Records of Intelligence Activities of Major General Makoto Onodera: 1935–1946, 35. Wilno (current Vilnius, Capital of Lithuania) was a debated ground between Poland and Lithuania back then, moreover the city was a philosophical capital of Belarus nationalism. The complexity of the political circumstance made Onodera’s plan difficult.

48.     Onodera, Y. Records of Intelligence Activities of Major General Makoto Onodera: 1935–1946, 36.

49.     Onodera, Y. On the Shore of the Baltic Sea. Kyodo Tsushin, Tokyo, 1985, 54. The event had been repeatedly mentioned by Yuriko Onodera in her various memoirs between the 1980s and the 1990s. It is unclear whether the Japanese covert operations against the Soviet Union had related to the death of Tukhachevsky.

50.     Onodera, Y. Records of Intelligence Activities of Major General Makoto Onodera: 1935–1946, 33.

51.     Erickson, J. The Soviet High Command: A Military-Political History 1918–1941. Macmillan & Co., Ltd., London, 1962, 449.

52.     Yomiuri Shimbun, 29 January 1972, 19.

53.     U.S. Department of State. Documents on German Foreign Policy 1918–1945: Series C (1933–1937). The Third Reich – First Phase Volume III. United States Government Printing Office, Washington D.C., 1959, 480.

54.     Ibid., 666. Memorandum by the director of Department 4 of the German Foreign Ministry on the visit of Chinese diplomatic representative to the Ministry.

55.     Degras, J. Soviet Documents on Foreign Policy. Volume 3: 1933–1941. Oxford University Press, New York, 1953, 12.

56.     Ibid., 13. As CER existed deep inside Manchukuo, the Soviet Foreign Ministry had no other choice but to allow the transportation of Japanese troops by CER and approve its anti-bandits operations across the railway.

57.     On 2nd May 1933, Litvinov, Soviet Foreign Minister suggested Japanese Ambassador Ota in Moscow the purchase of CER by Manchukuo (Degras, J. Soviet Documents on Foreign Policy. Volume 3: 1933–1941, 17).

58.     Yomiuri Shimbun, 25 January 1972, 21. The agreement was formally signed in Tokyo on 23rd March 1935.

59.     Yomiuri Shimbun, 16 February 1971, 21.

60.     McKenzie, K. E. The Soviet Union, the Comintern and World Revolution: 1935. – Political Science Quarterly, 1950, 65, 2, 220.

61.     Yomiuri Shimbun, 25 January 1972, 21.

62.     Yomiuri Shimbun, 26 January 1972, 21; Tokyo Asahi Shimbun, 14 May 1936, 2. Colonel Hikosaburo Hata, military attaché in Moscow, provoked the Soviet generals with highly political joke (“After returning to Japan, I will give an order to provide cans of Japanese Sake to every soldier on the border, thus the Soviet Army should do the same with vodka. If we have enough alkanols, there shall be no more border conflicts”), Marshal Voroshilov and Marshal Budyonny took it seriously while Marshal Yegorov laughed at it.

63.     OGPU stood for Ob''edinennoe gosudarstvennoe politicheskoe upravlenie pri SNK SSSR, or the ‘Joint State Political Directorate’ in English. It was established in 1923, then was incorporated into NKVD in July 1934.

64.     Conquest, R. The Great Terror: Stalin’s Purge of the Thirties. The Macmillan Company, New York, 1968, 547.

65.     Main, S. J. The arrest and ‘Testimony’ of Marshal of the Soviet Union M. N. Tukhachevsky (May-June 1937). – The Journal of Slavic Military Studies, 1997, 10, 1, 152.

66.     JACAR, 18. Recent Soviet Internal Affairs (Considering Tukhachevsky Plot) (Kotani Etsuo, Infantry Captain). Ref.: B02030915600, 15. (Access Date and Time: 28th January 2017 08:30 AM).

67.     Yomiuri Shimbun, 28 January 1972, 21. Hiroshi Onouchi, the last Japanese military attaché in Riga (1939–1940), also noted the Soviet surveillance was really tight when he traveled to Moscow in August 1939 (Yomiuri Shimbun, 28 March 1974, 3).

68.     Yomiuri Shimbun, 25 March 1974, 3.

69.     Raštikis, S. Fighting for Lithuania. War Memories. Volume 1. Lietuvių dienos, Los Angeles, 1956, 475–476.

70.     Yomiuri Shimbun, 28 March 1974, 3; 1 April 1974, 5.

71.     ERA.495.11.43.14. The arrival of Onouchi in Helsinki was reported to the Estonian General Staff by Aleks (Aleksei) Kurgvel, Estonian military attaché in Finland.

72.     Momose, H. Japan’s relations with Finland, 1919–1944, as reflected by Japanese source materials. – Slavic Studies, 1973, 17, 27. Momose interviewed Onouchi and acquired the information.

73.     Shigemitsu, A. Russians in My Memories. Self-publishing, 1986, 68. Shigemitsu was interpreter at the both occasions.

74.     Riksarkivet Arninge (Swedish National Archives, Arninge) 22-2-98 (980222-9972), 15. Nishimura had resided in Jungfrugatan 23, Stockholm ever since November 21st 1939.

75.     Shigemitsu, A. Russians in My Memories, 68.

76.     Riksarkivet Arninge (Swedish National Archives, Arninge), Stockholm, 22-2-98 (980222-9972), 15. Onouchi took a direct flight from Riga to Stockholm.

77.     Ulkoministeriönarkisto (Finnish Ministry of Foreign Affairs Archives), Helsinki, FB6-6-0, 96.

78.     Muzeum Wojska Polskiego w Warszawie (Polish Army Museum), Warsaw, 7W2C, Memoir of Michal Rybikowski, 8–9. It was Michal Rybikowski, who was the former informant of the Japanese military attaché office in Riga. On the 26th, Onouchi and him took a flight from Riga to Stockholm. Rybikowski was also hired by the Japanese military attaché office in Stockholm and worked for the office until 1944.

79.     LVVA, 2942-1-1586, 39.

80.     Muzeum Wojska Polskiego w Warszawie (Polish Army Museum), Warsaw, 7W2C, Memoir of Michal Rybikowski, 7.

81.     Okabe, N. Disappeared Yalta Telegram, 149: Muzeum Wojska Polskiego w Warszawie (Polish Army Museum), Warsaw, 7W2C, Memoirs of Michal Rybikowski, 8.

82.     Muzeum Wojska Polskiego w Warszawie (Polish Army Museum), Warsaw, 7W2C, Memoirs of Michal Rybikowski, 8.

83.     Rybikowski’s Manchukuo passport was soon replaced with that of Japan, in Stockholm, in 1941. The puppet state of Manchukuo was recognized only by few states in Europe and the validity of the passport was questionable. And, already in October 1939, the Soviet Union had started the stationing of its troops in Latvia according to the bilateral treaty. Both Onouchi and Rybikowski were probably concerned about the repetition of the Polish partition case in the Baltic States.

84.     Fujii, H. Human Source Management of the Japanese Army during Showa Period. Ushio Shobou Kojinsha, Tokyo, 2015, 229.

85.     Ito, M. The Rise and Fall of Military Factions. Volume 2. Ushio Shobou Kojinsha, Tokyo, 2016, 166.

86.     Yamazaki, M. Blitzkrieg over Poland. Gakken Publishing, Tokyo, 2010, 111.

87.    Osaka Mainichi Shimbun, 3 July 1937.


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