Had the Japanese succeeded in their last-ditch atomic effort, the world’s history might have been very different. By August 1945, Japan had abandoned the idea of bombing mainland America. Instead, Japanese leaders were planning to use what atomic weapons they could produce on the Allied invasion fleet that they believed would soon be off its shores.

We’ve just been through the annual commemoration and condemnation of America’s atomic bomb-dropping on Japan at the end of World War II. It’s little known, however, that at the same time that occurred, August 1945, Japan was desperately trying to perfect its own atomic bomb in Korea and may have tested one by then. The Japanese government was hoping to use it on the coming invasion of the home islands.

But the test was too late. Nearby Russia, sharing a border with Korea, knew about the Japanese atomic plants. Declaring war on Japan in those last tumultuous days, the Soviets invaded northern Korea, took the Japanese plants, and imposed tight secrecy. When, nearly two years later, they’d finished looting the Japanese atomic plants, they gave them to then fledgling North Korea. That’s the real beginning of today’s North Korean nuclear threat.

This history is little-known. As a result, Japan today is seen almost exclusively solely as a victim of the bomb.

But had the Japanese government succeeded in this last-ditch atomic effort, the world’s history might have been very different. Japan, by then, had abandoned the idea of bombing mainland America. Instead, Japan’s leaders were planning to use what nukes they could produce on the Allied invasion fleet that they believed would soon be off its shores.

Japan had been well-aware of early, revolutionary nuclear developments in the late 1930s. It had top physicists, like Yoshio Nishina, a friend of Nils Bohr, and Bunsaku Arakatsu, a colleague of Albert Einstein. Even before Pearl Harbor, Japanese physicists called for a Japanese atomic bomb program which did begin, but at a low priority because Japanese leaders thought the war would end quickly.

But as the war dragged on, the project rose in priority. The problem for Japan was not physics. They knew how to make an atomic bomb. After three decades of research, I’ve unearthed ample proof for that. The big problem was finding fissionable elements like uranium, separating it into bomb fuel, and engineering it into a bomb. All of Occupied Asia – Korea, China, Manchuria, and Japan – yielded the minerals and contributed with physics programs of their own. Northern Korea, with a huge industrial complex built by the Japanese before the war, provided the industry. Bomb-making was then an engineering feat which a crack group of Japanese physicists and engineers in Hungnam, Korea tackled.

Nishina and Arakatsu, respectively, headed Japanese army and navy pilot programs in Japan proper. They separated uranium and other fissionable elements in Tokyo and elsewhere early in the war. At first, the services were rivals and kept individual breakthroughs in-house. But as Japan’s war fortunes worsened, the services cooperated. Pilot separators were improved and shipped to Korea. It was there, free from the Allied bombing of Japan, that the final developments in the Japanese atomic program took place, although there are indications of pertinent activity elsewhere as well. David Snell, an army investigator in Korea and later respected Life Magazine correspondent, first reported in 1946 in the Atlanta Constitution that the result was the test-firing of a nuclear device off Korea.

But by then, America’s priorities had shifted. The Russians were now the new enemy. America needed nearby Japan as an ally against the Soviets. Japan, which had suffered the world’s first atomic attack, understandably, did not want it public that they’d tried to make and use one too. The U.S. wanted Japanese cooperation. It agreed to keep the project secret. Meanwhile, the Soviets, as they looted the plants, kept northern Korea off limits to the outside world. They even shot down American planes nearing the area. Information about the Japanese plants in Korea was effectively stifled. Historians were kept in the dark.

However, by 1950, U.S. intelligence suspected the Japanese effort. “Of increasing interest have been recent reports dealing with an apparent undercover research laboratory by the Japanese at Hungnam,” says a typical report. “All reports agree that research and experiments on atomic energy were conducted.” American bombers repeatedly hit targets on the North Korean coast said to be “atomic.” As Allied troops fought into Hungnam, the New York Times headlined, “North Korean Plant Held Uranium Works” (26 October 1950). A story in the 28 November 1950 Canberra Times (Australia), began, “Atom bomb materials were being made at… Hungnam.”

Today, Japan is reliving its history. Tired of depending on the U.S. to protect it from its belligerent neighbor, North Korea, it’s debating whether to go nuclear again. And in that, it’s an irony that Japan gave North Korea the beginnings which have grown into a threat.

Why is this important today? First, history missed is history not learned. Japan’s little-known WWII project is a model of how a belligerent country smaller than the U.S. could mount such a program. We need that information to make sure it doesn’t happen again. Second, and probably more important, because this history was suppressed, some of North Korea’s secret sites may have been missed by U.S. targeteers, should targeting ever be needed. Most U.S. targeting falsely assumes North Korea’s nuclear program began in the mid-1950s. From a national security standpoint, there is a history of North Korea’s atomic works and underground silos that was missed.

Author’s Note: This little-known history is detailed in my new revised and greatly updated book, Japan’s Secret War, Third Edition: How Japan’s Race to Build its Own Atomic Bomb Provided the Groundwork for North Korea’s Nuclear Program,  published by Permuted Books, an affiliate of Simon & Schuster.

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The featured image is “A New Year’s card depicting the Hinomaru, a sunset and traditional Japanese homes,” and is in the public domain, courtesy of Wikimedia Commons.

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