Editor's note: Jin Shicheng, a special commentator on current affairs for CGTN, is a researcher at the Exhibition Hall of Evidence of Crimes Committed by Unit 731 of the Japanese Imperial Army. He also serves as a specially appointed research fellow at the International Peace Archives of Heilongjiang International University. The article reflects the author's opinions and not necessarily the views of CGTN.

During World War II, Japan secretly established Unit 731 in Harbin, China, that would go on to become the command center for planning and executing its germ-warfare program. In the shadowy space where boundaries between war and medicine were blurry, the unit carried out horrific human experimentation and launched germ-warfare operations under a veil of secrecy.

The rise and expansion of Unit 731 were not isolated acts of military extremism. They were backed by the full weight of the Japanese state. The central government, the Kwantung Army and even Japan's medical communities all played a role. Both the Ministry of the Army and the Kwantung Army invested heavily in this endeavor, providing the unit with manpower, resources and funding.

Looking at the timing, locations, scale and operational reach of Unit 731 and other epidemic prevention and water supply units, it becomes clear that germ warfare was not an auxiliary tactic but an increasingly central component of Japan's broader military aggression in China and across Asia. It was an integral part of Japan's invasion apparatus, revealing the deeply invasive and expansionist nature of Japanese imperialism at that time.

The formation of Japan's wartime system of medical-military collaboration in crimes

Following the enactment of the National Mobilization Law in 1938, Japan began forcibly institutionalizing and radicalizing military medical research. From 1931 to 1945, under the pressure of a wartime regime, Japan's public health agencies and medical institutions were systematically drawn into a nationalized and militarized policy framework. Within this framework, where the boundaries between war and medicine became increasingly blurred, Japan constructed an extraordinary wartime medical regime.

Under this system, professional organizations such as the Japanese Society of Pathology, the Japanese Society of Health and Human Ecology (formerly known as the Japanese Society of Race Hygiene) and the Kyoto Medical Association became actively involved in the war of aggression against China. Meanwhile, student medical units and civilian healthcare workers were also mobilized en masse to serve military objectives.

Unit 731 established steady and structured personnel pipelines with institutions including the Army Medical School of Japan, Kyoto University (formerly known as Kyoto Imperial University), and the University of Tokyo (formerly known as Tokyo Imperial University). Japan's medical establishment provided the unit with nearly a hundred doctors and technical specialists. These people held core leadership roles within Unit 731, overseeing departments, branches, research divisions, administrative units and training programs. They were deeply involved in every phase of the unit's establishment and expansion.

At the same time, the epidemic prevention and water supply units maintained complex and ongoing ties with Unit 731 through personnel transfers, coordinating operations and collaborating in germ warfare. Unit 731, in effect, stood as the central pillar of Japan's biological warfare system.

The construction of Japan's germ warfare crime system in aggression against China

Between 1938 and 1945, under the direct leadership and participation of Unit 731, Japan built an extensive network of biological warfare units across its occupied territories. Prominent among them were the Epidemic Prevention and Water Purification Department of the north China Army stationed in Beijing (Unit 1855), the central China unit in Nanjing (Unit 1644), and the south China unit in Guangzhou (Unit 8604).

As Japan's army established epidemic prevention institutions throughout the occupied regions, their coverage steadily expanded and their internal operations became more sophisticated and systematized. In a wartime report published by Shiro Ishii, head of Unit 731, titled "Operational Outcomes of Newly Established Army Epidemic Prevention Divisions During the Marco Polo Bridge Incident, Future Military Strategy, and the Effectiveness of Vaccination Measures" (included in Volume II, No. 99 of the Research Report on Epidemic Prevention of Army Medical School), these units were classified into four distinct types: "fixed," "mobile," "temporary" and "independent."

By the end of the war, the Japanese military had established a total of 63 epidemic prevention and water supply units. Their footprint extended across most of China and into other parts of East and Southeast Asia, including Korea, Malaysia, Singapore and Thailand.

These epidemic prevention units, operating under the guise of public health support, appeared on the surface to be responsible for assisting combat troops with disease control and water supply. In reality, they served as a cover for far more sinister purposes.

Behind the euphemistic term "epidemic control operations," medical researchers within this system secured massive government funding and generous personal compensation under the pretexts of "scientific" and "military" research. Shielded by the secrecy of their missions, they carried out large-scale human experimentation, experiments so inhumane and ethically indefensible that they could not have been attempted within Japan itself.

From military medical research to battlefield experimentation

Human experimentation and biological warfare, spearheaded by Unit 731, were carried out under the banners of "national interest," "scientific inquiry" and "medical advancement." Behind these justifications, however, lay acts of unspeakable cruelty. Thousands of Chinese, Soviet and DPRK civilians and prisoners were subjected to fatal experiments. These atrocities were not only a shared criminal enterprise between Japan's wartime military and medical establishment, but also a profound and indelible stain on the history of Japanese medicine.

As Japan expanded its occupied territories and scaled up the organizational structure of its epidemic prevention and water supply units, such crimes gradually spread across multiple regions. Human experimentation and germ warfare were not limited to these units alone. Army hospitals and front-line medical teams also exploited prisoners of war, performing procedures such as live vivisection.

One revealing piece of evidence, the classified document titled Top Secret: Results of the Mongolian Garrison Army's Winter Hygiene Research, lays bare the reality that human experimentation during this period was not the work of isolated actors. Rather, it was a systematic war crime enabled by close collaboration between the Japanese military and medical establishments, all under the cloak of "scientific research."

From January 31 to February 11, 1941, the Japanese North China Area Army's Mongolian Garrison organized a so-called "Winter Hygiene Research Team" in Sunite Right Banner of Xilingol League (in present-day Inner Mongolia). Over that period, eight Chinese male civilians aged between 15 and 50 were subjected to live human experiments. After the experiments were completed, the victims were executed one by one and buried. A perfunctory memorial ceremony followed.

The document contains explicit instructions from the Army surgeon general and includes five separate reports from the research team, detailing the operation's timeline and execution. The record leaves no doubt that these experiments were conducted under the direct supervision of the Mongolian Garrison's medical command.

Moreover, it reveals the extensive and coordinated participation of Japan's wartime military-medical apparatus, including divisional and brigade-level hygiene teams, army hospitals and epidemic prevention units, in both organizing and executing human experimentation.

Japan's germ warfare in China was the product of both institutional and individual forces. On the one hand, it was driven by the state's wartime apparatus backed by national politics, social institutions and the medical establishment. On the other, it was enabled by the personal choices of medical professionals who actively conformed to and served the goals of war. Unit 731 became the nexus where these two forces – state machinery and personal choices – met and reinforced one another.

The research on pathogens conducted by Unit 731 was never intended to advance medicine or science. From its inception, the unit existed to serve Japan's war of aggression. This instrumental use of science for military conquest was evident in every stage of its establishment and expansion. Germ warfare became a core strategy in Japan's invasion of China and other parts of Asia, forming an integral component of its broader war machine.

The human experimentation and germ warfare carried out by Unit 731 constituted grave violations of medical ethics and international law. These actions inflicted irreversible harm on countless innocent civilians, as they destroyed lives and devastated entire communities.

More than just a betrayal of the fundamental mission of medicine, these atrocities represented a brutal assault on human dignity and the right to life. They were a profound affront to the very moral foundations of human civilization.

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