SINGAPORE, Aug. 14 (Xinhua) — “More than 80 years have passed, and only now are we beginning to realize how much Japan still hasn’t told us,” mentioned Lim Shao Bin, a Singaporean historian who has spent a long time tracing Japan’s organic warfare actions in Southeast Asia, in a latest interview with Xinhua.
As every new discovery serves as a reminder of how a lot stays undocumented, Lim mentioned that filling these gaps would require broader worldwide cooperation amongst governments and students — not solely to advance analysis throughout disciplines, but additionally to encourage the discharge of extra historic data.
Since the Eighties, Lim has collected wartime Japanese paperwork from secondhand bookstores and authorities archives in Japan. Over the previous decade, his analysis has targeted on Unit 9420, a lesser-known organic warfare unit of the Japanese Imperial Army that operated in Southeast Asia.
Unit 9420 was constructed as a part of Japan’s broader organic warfare community, with personnel drawn from established items together with Unit 731 in Harbin, and different items in Nanjing and the Japanese homeland.
According to Lim, Unit 9420 “created an entire production line for germ bombs in Singapore and what is now Malaysia.” Vegetables have been cultivated to feed rats. Rats have been bred to supply fleas. The fleas have been then contaminated with plague micro organism earlier than being packed into glass bombs and transported to battlefields.
Headquartered in Singapore, the unit maintained branches throughout present-day Malaysia, Indonesia, the Philippines, Thailand, Vietnam and Myanmar.
“The Japanese military came to Southeast Asia because the climate was ideal,” Lim mentioned. Japanese researchers had concluded that fleas reproduced most effectively at temperatures between 27 and 30 levels Celsius and humidity ranges of round 90 %.
Many of those findings appeared in “Oka 9420 Unit, Japanese South Army BW Troop,” a e-book Lim co-authored with Chinese scholar Wang Xuan and printed in 2025.
Yet new proof has continued to emerge.
Among probably the most important is a lately disclosed testimony preserved at Britain’s National Archives from a former prisoner of warfare recognized as W. B. Williams, which can provide new clues that British prisoners have been additionally subjected to human experimentation.
Captured in Singapore in February 1942, Williams wrote that he and lots of different prisoners have been vaccinated and inoculated. Blood samples have been taken, and “a glass tube was inserted in the back passage.”
Within days, he recalled, giant numbers of prisoners, together with himself, developed extreme complications, diarrhea, dysentery and stomach signs.
According to his testimony, comparable procedures have been repeated thrice over three years at totally different camps, every adopted by the identical signs.
“If that is not experiments, I don’t know what else you call it,” Williams wrote.
“Before this, we had not come across any records indicating that British nationals were also subjected to human experimentation,” Lim mentioned.
The risk, nevertheless, didn’t come solely as a shock to Lim. In his 2025 e-book, he had already raised questions on whether or not Unit 9420 carried out human experiments on British nationals.
In June 1944, he famous, 17 British prisoners of warfare held in Singapore contracted scrub typhus — a illness that was not endemic to Singapore on the time — and three died.
Separately, a medical report produced by Unit 9420 recorded that navy docs had efficiently remoted the associated pathogen from wild rats and transported it again to “Syonan-to,” the title utilized by Japan for occupied Singapore.
“The disease wasn’t native here,” Lim mentioned. “It was brought in.”
Lim additionally pointed to a different unresolved chapter.
After Japan’s give up, the United States dispatched a number of groups to research Unit 731. The unit reportedly handed over roughly 8,000 pathology slides to the American facet. But the supplies have been by no means disclosed to the general public, nor have been any warfare accountability proceedings ever introduced in opposition to members of the unit.
“International cooperation is essential,” mentioned Lim, noting that solely coordinated efforts by governments and analysis establishments can encourage Japan, the United States and different nations to launch extra archival supplies.
“If it’s only individual scholars or universities asking for disclosure, it’s very difficult to make progress,” he added.
For Lim, worldwide cooperation extends past opening archives. Understanding the surviving proof more and more requires experience from a number of disciplines.
He recalled discovering a 1942 stock itemizing a whole bunch of chemical brokers transferred from Unit 731 headquarters to Unit 9420 for six months of use. Every entry was recorded in Japanese katakana. “If you don’t have specialists from that field, it’s almost impossible to interpret.”
“We need people from many different fields if we are to fully expose this historical malignancy,” he mentioned.
In June this yr, Singapore’s Channel NewsAsia launched the documentary Inside Unit 731: Japan’s Secret Human Experiments. Lim mentioned many viewers in Singapore have been shocked to be taught that the nation had been linked to Japan’s organic warfare program.
“Many people assumed Unit 731 was only a story about China,” he mentioned. “Now that Singapore’s broadcaster has told this history, audiences, including many in Europe and North America, are realizing that it involved much more.”
For Lim, documenting the historical past of Unit 731 and its affiliated items is just not merely an train in reconstructing the previous. It can be about understanding the warning indicators that precede future conflicts.
Japan’s historical past of navy enlargement, he argued, demonstrates that preparations for warfare usually start years earlier than open hostilities.
“The international community must remain vigilant,” he mentioned. “There should be more effective supervisory mechanisms for former aggressor states to prevent similar tragedies from happening again.”