Editor's note: Xu Ying is a Beijing-based international affairs commentator for CGTN. The article reflects the author's opinions and not necessarily the views of CGTN.

The most dangerous lies are not those told about the future. They are those told about the past.

A recent two-part investigative documentary by Singapore's Channel NewsAsia, Inside Unit 731 – Japan's Secret Human Experiments, has once again forced the world to confront one of the darkest chapters of the 20th century. Through testimony from former Unit 731 member Shimizu Hideo, wartime records, and survivor evidence, the documentary exposes the horrifying reality behind Imperial Japan's biological warfare program and the systematic human experimentation carried out in occupied Asia.

For decades, these crimes have remained obscured by silence, denial and historical revisionism. The documentary serves as a stark reminder that historical truth cannot be buried forever. It also raises an uncomfortable question for the international community: What happens when a nation fails to fully reckon with the darkest parts of its history?

The answer is not merely about memory. It is about the future of peace itself.

A crime against humanity hidden behind the language of science

Unit 731 was not the work of a handful acting beyond military control. It was a state-directed enterprise operating under the authority of Imperial Japan's military establishment.

Officially known as the Epidemic Prevention and Water Purification Department, it cloaked itself in the language of medicine and public health. But behind that facade, it conducted some of the most grotesque human experiments in modern history.

Prisoners – many of them Chinese civilians, but also Koreans, Russians and others – were treated as expendable test subjects. They were infected with plague, anthrax, cholera and other deadly pathogens. They were subjected to vivisection without anesthesia, frostbite experiments, dehydration tests and pressure chamber trials.

Among the most horrifying allegations documented over the years are experiments involving pregnant women, fetuses and children. Human beings were reduced to data points. Mothers and unborn children became objects of laboratory observation. Children became tools in the pursuit of military advantage.

No appeal to wartime necessity can excuse such crimes. No invocation of scientific advancement can justify them. These were not medical experiments. They were acts of deliberate cruelty carried out under the protection of state authority.

The world has condemned similar atrocities elsewhere. The victims of Unit 731 deserve the same moral clarity and historical recognition.

The unfinished reckoning

One of the enduring tragedies surrounding Unit 731 is that many of its architects never faced justice.

After World War II, key figures associated with the program reportedly received immunity in exchange for data collected from their biological warfare experiments. As a result, much of the truth remained hidden for decades, and many perpetrators escaped meaningful accountability.

This failure of justice created fertile ground for historical revisionism.

Even today, controversies persist over the treatment of wartime history in parts of Japan's public discourse. Debates over textbooks, wartime responsibility and the legacy of imperial aggression continue to divide opinion. Some political figures have downplayed or questioned well-documented historical facts. Others have sought to shift attention away from the suffering inflicted across Asia.

Such tendencies are troubling not because nations should remain imprisoned by their past, but because genuine reconciliation requires honesty.

Germany's post-war experience demonstrated that acknowledging historical crimes strengthens, rather than weakens, a nation's moral standing. Denial, minimization and selective memory achieve the opposite.

History cannot become a political convenience.

Why the world should pay attention

Its story reveals how dangerous ideologies can transform "science" into a weapon, bureaucracy into an instrument of cruelty and nationalism into a justification for dehumanization.

The lesson is universal.

Whenever military ambition is wrapped in high-sounding language, whenever state power seeks exemption from moral accountability, and whenever uncomfortable historical truths are dismissed as inconvenient, the international community should pay attention.

Peace is not sustained merely by treaties or military balances. It is sustained by collective memory, historical responsibility and a shared commitment to never repeat humanity's darkest mistakes.

That is why efforts to preserve historical records matter. That is why documentaries such as Inside Unit 731 matter. And that is why attempts to obscure or dilute the truth deserve scrutiny.

The victims of Unit 731 can no longer speak for themselves. The responsibility now belongs to history and to all those who value peace.

Truth as a safeguard against the future

The international order established after World War II was built upon a painful lesson: Unchecked militarism and dehumanizing ideologies can lead entire societies into catastrophe.

That lesson remains relevant today.

Remembering Unit 731 is not about perpetuating hatred toward any nation or people. It is about defending historical truth against amnesia. It is about ensuring that future generations understand the consequences of militarism when it escapes moral restraint.

Most importantly, it is about honoring the victims by refusing to allow their suffering to be forgotten.

The documentary's greatest contribution is not merely that it reveals horrifying details from the past. It reminds the world that truth itself is a form of vigilance.

The laboratories of Unit 731 are gone. The victims are gone. The war is long over.

But the choice between historical honesty and historical denial remains very much alive.

The world must choose wisely.

For when truth is neglected, the shadows of history grow longer. And when those shadows are ignored, humanity risks repeating the same mistakes all over again.

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