Page 55 - Unit 731

On 21 March, the Washington Joint Staff replied by telegram to Gen. Douglas MacArthur: ‘Based on the following factors, the Soviet Union is approved to
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interrogate Shirō Ishii, Army Colonel Masumi Ota and Hitoshi Kikuchi about biological warfare. … Before the interrogation, it is a must to inform the
Japanese experts of biological warfare not to mention the US interrogation to the Soviet Union’. 24
The US agreed to allow the Soviet Union to investigate regarding biological warfare, but in order to keep the information to themselves, the US
discussed with Ishii and the other members not to disclose any detail of the US investigation or any important information regarding biological warfare to
the Soviet Union.
This act is the same as the US investigation of the members of Unit 731—compromise before providing declarations.
The Secret Deal in the Telegram
On 6 May 1947, the Supreme Commander for the Allied Powers sent an urgent telegram, no. 52423, to the US Department of Defense. It contained five
parts:

Statements obtained from Japanese here confirm statements of USSR prisoners Kawashima and Karasawa contained in copies of interrogations given US by USSR.
Experiments on humans were known to and described by three Japanese and confirmed tacitly by Ishii; field trials against Chinese Army took place on at least three occasions; scope of program
indicated by report of reliable informant Matsuda that 400 kilograms of dried Anthrax organisms destroyed at Pingfang in August 1945; and research on use of BW against plant life was carried out.
Reluctant statements by Ishii indicate he had superiors [possibly General Staff] who knew and authorized the program. Ishii states that if guaranteed immunity from ‘War Crimes’ in documentary form
for himself, superiors and subordinates, he can describe program in detail. Ishii claims to have extensive theoretical high-level knowledge including strategic and tactical use of BW on defense and
offense, backed by some research on best BW agents to employ by geographical areas of Far East, the use of BW in cold climates.
(A) Statements so far have been obtained by persuasion, exploitation of Japanese fear of USSR, and desire to cooperate with US. Large part of data including most of the valuable technical BW
information as to results of human experiments and research in BW for crop destruction probably can be obtained in this manner from low echelon Japanese personnel not believed liable to ‘War
Crimes’ Trials.
(B) Additional data, possibly including some statements from Ishii probably can be obtained by informing Japanese involved that information will be retained in Intelligence channels and will not,
be employed as ‘War Crimes’ evidence.
(C) Complete story, to include plans and theories of Ishii and superiors, probably can be obtained by documentary immunity to Ishii and associates. Ishii also can assist in securing complete
cooperation of his former subordinates.
None of above influences joint interrogations to be held shortly with USSR under provisions of your Radio W-94446.
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Adoption of method in part Three-B. above recommended by CINCFE. Request reply soonest. [See Fig. 36.]
‘… could inform the Japanese that, the related information would be kept as important source and would not be used as war crime evidence in the Trial’.
This is US Forces in Japan’s suggestion to the US Department of Defense in order to collect information and data on biological warfare and human experimentation, and they also suggested that
‘Plans and information from Shirō Ishii and his higher authorities may collected by exempting them from trial in written form’. 26
It is hard to follow all comments from the Washington headquarters in 1946 and 1947, but simply put, the Supreme Commander of the Allied Powers was
able to use all means and methods to investigate Japan, Unit 731, and war-related individuals in order to collect information beneficial to the US.
During the investigation and interrogation of members of Unit 731, the US implied to members of Unit 731 that their disclosures would not be used as
evidence in the Tokyo Trial. Investigators were scientists and experts mainly from the Detrick military base, and the content of investigations was mostly
related to biological weapons, strategies of biological warfare and results of experiments.
I suspect that from the beginning of these interrogations, the US focused on acquiring technical information regarding biological warfare, and had no
concern whether the information would be used as evidence in the Trial.
United States Department of Defense Concerns
The US Department of Defense sent a telegram to the Supreme Commander of the Allied Powers Law Department on 3 June 1947:
… all evidence and information provided by Shirō Ishii and members of his division must be provided to the States in a telegram as soon as possible, especially evidence from Shirō Ishii and his
members that the US agreed to exempt them from trial in written form. Which countries among our allies accuse Shirō Ishii and his members? Are Shirō Ishii and his members included in the list of
war criminals waiting to undergo trial? 27
The Supreme Commander of the Allied Powers Law Department replied to the United States Department of Defense on 6 June 1947:
1. The reports and files of the Legal Section on Ishii and his co-workers are based on anonymous letters, hearsay affidavits and rumours. The Legal Section interrogations, to date, of the numerous
persons concerned with the BW project in China, do not reveal sufficient evidence to support war crime charges. The alleged victims are of unknown identity. Unconfirmed allegations are to the
effect that criminals, farmers, women and children were used for BW experimental purposes. The Japanese communist party alleges that: ‘Ishii BKA’ [Bacterial War Army] conducted experiments
on captured Americans in Mukden and that simultaneously, research on similar lines was conducted in Tokyo and Kyoto.
2. None of Ishii’s subordinates are charged or held as war crime suspects, nor is there sufficient evidence on file against them. Ishii’s possible superiors, who are now on trial before IMTFF, include
Umezu, Commander, Kwantung Army, 1939–44, Minami, Commander, Kwantung Army 1934–36, Koiso, Chief of Staff, Kwantung Army 1932–34, Tojo, Chief of Staff, Kwantung Army 1937–
38.
3. None of our Allies to date have filed war crimes charges against Ishii or any of his associates.
4. Neither Ishii nor his associates are included among major Japanese war criminals awaiting trial. 28
On 22 June 1947, the US Department of Defense requested further information from the Supreme Commander for the Allied Powers:
… evidence now in its possession warrants opinion that Japanese BW group headed by Ishii did violate rules of land warfare. We are satisfied evidence now in possession Legal Sect SCAP does not
warrant such charge against and trial of Ishii and his group. Must have info re all possible proof re Ishii BW group participation in activities that could be considered War Crimes under rules of land
warfare before reaching decision reurad C 52423 dtd 6 May 47. 29
Even though the US understood Ishii’s actions were war crimes, the evidence further confirms he was not to be accused and undergo trial or be on the list
of war criminals. In order to prevent Ishii’s evidence being disclosed in public, the US deliberately ignored the culpability of Unit 731 and Japanese troops.
Regarding this, although the US agreed with the suggestions in the telegram of 6 May, there were still concerns.
On 27 June 1947, the Supreme Commander for the Allied Powers Law Department sent an urgent telegram to the Department of Defense providing
details from a report that investigated Unit 731 for war crimes, and concluded that ‘Japanese BW group headed by ISHII did violate rules of land warfare,
but this expression of opinion is not a recommendation that group be charged and tried for such’. 30

Instruction from the Joint Chiefs of Staff
The Joint Chiefs of Staff sent an order to Douglas MacArthur on 13 March 1948 in reply to telegram no. 52423 of 6 May 1947. The swift reply that
MacArthur had requested in his telegram took ten months. The content of the telegram is as follows:
Reports by technical experts who have returned from your theatre indicate that to date necessary information and scientific data have been obtained to your satisfaction. Suggest your recommendation
Part 3 B and 5 be resubmitted for further consideration if and when you consider necessary. 31