On 18 August 2025, the Russian Federal Security Service [FSB] (Omsk office) declassified and released from its archives a batch of materials related to Imperial Japan’s bacteriological warfare program and the creation of the notorious Detachment 731. Today we’ll be presenting a translation of the initial four-page ‘Special Report’ described below. Also included in the FSB drop, coming soon to this website, are the four-page interrogation of a bacteriologist who participated in Japan’s program to develop weapons (10 February 1948), and a lengthy (16-page) transcript of the bacteriologist’s hand-written statement on how the program operated (17 February 1948). Because of its size, the last document will be published in installments.
Background: During the Manchurian strategic offensive operation (August 9–19, 1945), Red Army units defeated the main forces of the Japanese Kwantung Army and its satellites within 10 days.
On August 14, 1945, Emperor Hirohito of Japan signed a decree on unconditional surrender, and two days later, on August 16, the commander of the Kwantung Army, General Otozō Yamada, ordered the cessation of hostilities.
The Japanese General Staff had been planning to use bacteriological weapons directly during the offensive against the Red Army in order to disable its manpower, and also, in the event of the retreat of the Japanese troops, to infect the abandoned territory in order to cause mass epidemics in the enemy troops and among the civilian population.
For this purpose, in 1935 and 1936, units were formed in Manchuria (detachments No. 731 and 100 with their subordinate branches), engaged in the development of bacteriological weapons and the study of methods for its operational employment.
During the Soviet-Japanese conflict near the Khalkhin-Gol river in 1939, during the retreat of the Japanese troops, officers of detachment No. 731 poured several cylinders with typhoid, paratyphoid, and dysentery bacteria into the Khalkhin-Gol river in order to poison the Red Army soldiers and Mongolian cattle breeders.
The most aggressive activities of specially created bacteriological detachments and their branches were carried out against China in 1940–1942; experiments on living people and testing methods of infecting flora and fauna were actively practiced in 1941–1945, and acts of sabotage were carried out in 1944–1945.
The lightning offensive of the Soviet troops thwarted the plans of the Japanese military to use bacteriological weapons in hostilities. In order to hide any traces of criminal activity, the Kwantung Army command was forced to order the destruction of the surrendered detachments No. 731 and 100, their branches, laboratory base, accumulated stocks of bacteriological weapons, documentation, experimental results, etc.
During an interrogation on December 1, 1949 in Khabarovsk, General Yamada testified that “…the Soviet Union’s entry into the war against Japan and the swift advance of the Soviet army into the depths of Manchuria offered us an opportunity to use bacteriological weapons against the USSR and other countries.”
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During the defeat of the Kwantung Army, more than 600,000 Japanese generals, officers and soldiers surrendered to the Soviets. In 1945–1948, the Soviet state security agencies searched for Japanese servicemen and civilians involved in the development of the bacteriological weapons and the methods of their employment in POW and internment camps.
In early February 1947, the head of the Ministry of Internal Affairs of the USSR Department for the Khabarovsk Krai, General Lieutenant Ivan Dolgikh, sent a special message to Colonel General Sergo Goglidze, the accredited officer of the MGB of the USSR for the Far East, “On Japan’s preparation of bacteriological warfare against the Soviet Union.”
The document stated: “In the case of bacteriological specialists of the Japanese army captured by the Soviet troops, the Ministry of Internal Affairs of the Khabarovsk Territory established through operational investigation that the Japanese military, preparing an attack on the Soviet Union from the Manchurian bridgehead, was actively preparing the use of bacteriological means of mass human extermination.
“Scientific and experimental work was carried out with all types of plague, anthrax, gas gangrene, typhus, typhoid, paratyphoid, dysentery, cholera, infectious hemorrhagic fever (the so-called “Songo”), and glanders, directed at: establishing the most effective type of pathogens for mass infection of people and livestock, methods of military and sabotage use, chiefly in the conditions of the Far East, and the mass production of pathogens, as well as bacteria for the destruction of bread grains and vegetables.
“In order to test the action of various bacteria, experiments were continuously carried out on humans in the detachment, for which Russians, Chinese, Manchurians, and Japanese sentenced to death were kept in the prison of the detachment, delivered to the detachment by the Harbin military mission and the gendarmerie in especially secret procedures.
“Every year, as a result of these experiments, more than 3,600 people were killed in the detachment.”
The document drew attention to cases of the use of bacteriological weapons by Japanese troops against the Soviet Union and China:
“In 1939, during the events on Khalkhin-Gol, a special detachment of ‘death squads’ under the leadership of General Ishii, on the orders of the former commander-in-chief of the Kwantung Army, General Kenkichi Ueda, carried out a sabotage operation against Soviet and Mongolian troops to infect the lake and river Khalkhin-Gol with typhoid, paratyphoid and dysentery bacteria.
“In 1940, on the orders of the former commander-in-chief of the Kwantung Army, General Yoshijirō Umezu, and the former commander-in-chief of the expeditionary forces in Central China, Marshal Shunroku Hata, who were acting on the orders of the Japanese General Staff, a special expedition led by General Shirō Ishii carried out a combat operation in Central China, using an airplane to drop fleas infected with the plague against the Chinese troops in the Ningbo area, causing a strong outbreak of the plague among the Chinese population and soldiers, which took the lives of thousands.
“In 1941 and 1942, a similar operation of the employment of plague against Chinese troops was repeated in Central China by special expeditions of the Isia detachment. In 1941 this was in the Changde district, and in 1942, in the Zhegan district. Moreover, the operations carried not only an experimental, but also a tactical nature of the mass destruction of Chinese soldiers, connected with the so-called Zhegan operation for the strategic withdrawal of Japanese troops in this area.”
In conclusion, Lieutenant General Dolgikh noted in his special report:
“An inquiry established that by the time of Germany’s treacherous attack on the Soviet Union and the preparation of Japan’s attack on the Soviet Union from the Manchurian bridgehead by detachment No. 731, the main research work related to the preparation of a bacteriological attack on the Soviet Union had been completed.”
The following is the translated Special Report.
1 February 1947
No. 250194
S P E C I A L R E P O R T
on Japan’s preparation for bacteriological warfare against the Soviet Union
The UMVD for the Khabarovsk Krai on the matter of bacteriological specialists of the Japanese Army, taken prisoner by Soviet troops, has established through operational investigatory means, that the Japanese military, preparing a military attack on the Soviet Union from the Manchurian bridgehead, actively prepared bacteriological agents for mass human extermination.
It was for this purpose, at the order of the former military Japanese minister, General ARAKI, under the direct supervision of the prominent Japanese professor of bacteriology General-Lieutenant SHIRŌ ISHII (head of the bacteriology department at the military medical academy in Tokyo), that a special detachment was built in 1936 for the Kwantung Army in the city of Harbin, which was given the cover name “counter-epidemic detachment for the precautionary supply of water for the Kwantung Army,” and afterwards was known as “detachment No. 731.”
General ISHII was named the detachment leader, dually subordinate: to the commander in chief of the Kwantung Army and the chief of the General Staff of Japan.
By order of the Army Ministry of Japan, this detachment utilized the services of a number of prominent bacteriological specialists who, under the supervision of General ISHII, immediately began their scientific research work, under the guise of “Anti-epidemic service,” to study bacteriological agents for an attack, and the means to distribute them.
At the same time as this, some 40 km from the city of Harbin, in the area of Pingfang, Japanese construction organizations, under the immediate observation of the Harbin gendarmerie, quickly started large-scale construction of a special integrated plant for detachment No. 731.
By 1938, construction and equipping of this plant was complete. Several large buildings were build there for the laboratories and offices, spaces for the mass production of bacteria, equipped with powerful boilers, special equipment with a conveyor system, an airfield and hangars, a garage for 500 vehicles, and a special detention building for test prisoners and a crematorium to cremate the bodies; a machine shop, glass-blowing shop, large depots with railway access lines from the Pingfang station, an electrical power plant, cold storage units, drying compartments, residential buildings, barracks, and utility buildings for detachment personnel.
In the Anda area, 100 km from the city of Harbin, a special test range was outfitted for the performance of various bacteriological tests in field conditions.
As a result, all of the departments and branches of detachment No. 731 were concentrated in the Pingfang area, working to prepare the active bacteriological warfare weapons, and the detachment’s former premises in Harbin served as the location for those departments conducting anti-epidemic work.
All of the work of detachment No. 731 at Pingfang was placed under the strictest security. To ensure secrecy and support the objectives of the counterintelligence service, a special gendarme branch was assigned to the detachment.
All of the workers were warned of the absolute necessity of complete confidentiality. New arrivals to the detachment must undergo a special political and background check.
Strict access control was introduced. Every visitor is granted access to the detachment via special passes under mandatory escort by a security officer. Electric current is fed into the wire fence surrounding the premises.
By special order of the commander in chief of the Kwantung Army, aircraft are prohibited from flying over the detachment premises.
The annual budget for detachment No. 731 for scientific research activities, housing personnel, and construction and repair work was set by the Japanese Army Ministry at 10 million yen.
Scientific research and experimental operations were conducted for a variety of plague types: anthrax, gas gangrene, typhus, typhoid, paratyphoid, dysentery, cholera, infectious hemorrhagic fever (also known as “Songo”), and glanders, directed at: establishing the most effective type of pathogens for mass infection of people and livestock, methods of military and sabotage use, chiefly in the conditions of the Far East, and the mass production of pathogens, as well as bacteria for the destruction of bread grains and vegetables.
In order to test the action of various bacteria and methods of infection, experiments were continuously carried out on humans in the detachment, for which Russians, Chinese, Manchurians, and Japanese sentenced to death were kept in the detachment’s detention building, delivered secretly to the detachment by the Harbin military mission and the gendarmerie.
Every year, as a result of these experiments, more than 3,600 people were killed in the detachment.
In 1939, during the events on Khalkhin-Gol, a special detachment of ‘death squads’ under the leadership of General ISHII, on the orders of the former commander-in-chief of the Kwantung Army, General KENKICHI UEDA, carried out a sabotage operation against Soviet and Mongolian troops to infect the lake and river Khalkhin-Gol with typhoid, paratyphoid, and dysentery bacteria.
In 1940, on the orders of the former commander-in-chief of the Kwantung Army, General YOSHIJIRŌ UMEZU, and the former commander-in-chief of the expeditionary forces in Central China, Marshal SHUNROKU HATA, who were acting on the orders of the Japanese General Staff, a special expedition led by General ISHII carried out a combat operation in Central China, using an airplane to drop fleas infected with the plague against the Chinese troops in the Ningbo area, causing a strong outbreak of the plague among the Chinese population and soldiers, which took the lives of thousands.
In 1941 and 1942, a similar operation of the employment of plague against Chinese troops was repeated in Central China by special expeditions of the Isia detachment. In 1941 this was in the Changde district, and in 1942, in the Zhegan [sic] district. Moreover, the operations carried not only an experimental, but also a tactical nature in the mass destruction of Chinese soldiers, connected with the so-called Zhegan operation for the strategic withdrawal of Japanese troops in this area.
An inquiry established that by the time of Germany’s treacherous attack on the Soviet Union and the preparation of Japan’s attack on the Soviet Union from the Manchurian bridgehead by detachment No. 731, the main scientific research work related to the preparation of a bacteriological attack on the Soviet Union had been completed.
It was established that the most effective form of bacteriological agents for mass extinction is plague for humans, and anthrax for livestock.
Detachment No. 731’s personnel strength was brought up to 200.
The detachment set up mass production of bacteria and the breeding of plague-infected fleas.
In order to get an idea of the scope of the mass production of bacteria, suffice to say that by 1941, the production branch was fitted with 8 one-ton boilers and 4 two-ton boilers for the culture medium preparation for bacteria, 4500 cultivators for flea propagation, and an entire conveyer system for bacteria production.
According to conservative estimates, at 1.5 production capacity, in one month the detachment was able to produce 15 kilograms of fleas, and by bacteria type: plague – 160 kg, cholera – 320 kg, anthrax – 540 kg, and paratyphoid – 270 kg.
Under forced labor conditions, the available equipment made it possible to triple or quadruple production.
The following methods of distribution were adopted: aircraft, dispersal by dropping bombs with bacteria; artillery shells; mortars; special dispersion capsules; and the mass bacteriological infection of areas and reservoirs in territories to be left during withdrawal.
The scientific and experimental work in detachment No. 731 was conducted without pause until the bacteria distribution methods were perfected, and the work was carried out in low temperature conditions, in climates characteristic of northern Manchuria and the Soviet Far East.
In August 1945, part of detachment No. 731, engaged in bacteriological warfare preparations, was evacuated to Korea at the instruction of the Japanese command. At present, all detachment personnel and equipment are in the area of responsibility of the American occupation forces.
CHIEF OF THE UMVD FOR KHABAROVSK KRAI GENERAL LIEUTENANT DOLGIKH
Copy certified by: CHIEF OF THE INSPECTION SERVICE OF THE USSR MGB FOR THE FAR EAST MAJOR ORESTOV
5 April 1948
Translation © 2025 by Michael Estes and TranslatingHistory.org
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