Did You Know That Japan Had Its Own Nuclear Weapons Program?

  • Many years ago, I attended an anti-nuclear assembly in Wakayama, Japan. This was in about 2007 or 2008, well before the March 11, 2011 earthquake that would shut down the country’s entire nuclear power program. The speaker was very much against nuclear power and nuclear development of any kind. Her speech was rather self-congratulatory as she spoke of how Japan was one of the few powers that shunned nuclear weapons and is a totally peaceful country.

    A large part of the modern Japanese identity is that of a victim. To date, Japan is the only country that has been a victim of nuclear arms, and that fact makes up part of the modern Japanese person’s sensibilities when it comes to nuclear power and nuclear weapons. But some newly discovered history questions this idea…

    It is a story of top secret nuclear weapons programs, secret Nazi submarines, and an American military cover-up. This is the largely unknown story of Japan’s Nuclear Weapons Program and how it almost worked.

    The Nuclear Age


    Many are under the mistaken belief that people before the 1945 bombings of Hiroshima and Nagasaki had no idea about nuclear weapons and that Americans were the only ones who were able to make them. This is entirely incorrect. Marie Curie discovered radium in 1898 and her research was quickly followed up by Ernest Rutherford and Frederick Soddy who noticed that atoms broke down into other elements giving off huge amounts of energy at the same time. The military implications of this were noted right away as soon as 1914 science fiction luminary H. G. Wells wrote about atomic weapons in his book The World Set Free. In 1924, Winston Churchill said, “Might not a bomb no bigger than an orange be found to possess a secret power to destroy a whole block of buildings—nay to concentrate the force of a thousand tons of cordite and blast a township at a stroke?”

    Needless to say, most well-educated people of the time had a good idea that nuclear weapons were not only possible but would likely be used in future wars. I think that they did not see atomic weapons the same way we do. We think of nuclear weapons as apocalyptic, but they would have seen them as an economy of force. A smaller weapon that was capable of doing much more damage to the enemy. Look at how Churchill spoke about it. He seemed like he was just talking about a new type of explosive, and that was how it was commonly seen. This understanding of people’s perspectives on nuclear weapons is important to comprehend the rest of the story.

    In the pre-WWII days, Germany was the absolute height of world science and culture. Most of the world’s best scientists lived in Germany or in the quickly disintegrating Austro-Hungarian Empire. This was the birthplace of nuclear physics and where the idea of a nuclear weapon was conceived. But once Adolf Hitler came to power and enacted his Jewish repulsive measures, most of these great scientists, who were also often Jewish, fled the country to more open countries. Leo Szilard was one of those scientists who fled to London and there, in 1933, theorized about a “critical mass” that would be needed to start a chain reaction of neutrons that would create an explosion of unforeseen power. So now, scientists everywhere had all the pieces necessary to create nuclear weapons, but they faced two major problems.

    First was how to separate the necessary radioactive materials from the native elements. This would be the main engineering task that would plague all nations that would take part in nuclear research. Secondly, was the problem of acquisition. Uranium seemed to be the only source, and like Doc said in Back to the Future, you can’t exactly walk down to your neighborhood grocery store and pick up some uranium. It mostly came out of mines in the Congo.


    In order for Americans to create the “Fat Man” and “Little Boy” atomic bombs, it took a team of hundreds of the best scientists and the American government working with the United Kingdom in over 30 different sites. It was a massive undertaking that swept up vast amounts of time, workers, and money. This is where the story gets interesting… Japan managed to do almost the same amount as the Manhattan Project with a mere fraction of the staff, time, and money, and while under heavy bombardment by allied forces.

    Japan’s Nuclear Kingdom


    Japan had not only one Manhattan Project, but two! Japan had its own Einstein in the figure of Dr. Yoshio Nishina. He was a world-famous researcher and founded a nuclear research laboratory in Japan. In 1939, Nishina came to fully understand the possibility of using nuclear power to create weapons of mass destruction. He began to worry about the growing antagonism between Japan and America, and the possibility that America would be able to crack the code first and attack Japan. This would prove not only to be particularly predictive of future events but also seemingly clairvoyant because 1939 was the same year that then US President Franklin D. Roosevelt (FDR) ordered research on nuclear weapons to begin.

    Nishina campaigned the government to begin investigating on nuclear weapons post-haste, but it was not until 1941 that Nishina was tasked with developing a nuclear weapon. However, the Imperial Government did not put all of its eggs in one basket. The navy had secretly engaged in its own nuclear program and they codenamed their super weapon the “F-Go.” They charged the top researchers from Tokyo University in development. But, some time into development with little to no success, the navy decided to focus more on radar.

    Nishina charged full bore at the many diverse problems facing him. From here on out, we get into the realm of heavy speculation. Much of the information about Japan’s programs was classified at the time, and much of the paperwork about it was destroyed by the Japanese government in the closing days of the war. We do not know for sure how far Japan Nishina got. But many researchers agree that they got considerably farther than Nazi Germany did in its own projects. There are even reports that Nishina completed a working nuclear weapon and tested it! Is that even possible?! Let’s see…

    Nuclear Armed Japan

    From documents that we have found, we now know that Nishina had cracked all the engineering codes to build nuclear weapons and was constructing a centrifuge that would have been able to develop up to four nuclear weapons. This centrifuge was due to be completed mere days after the bombings of Hiroshima and Nagasaki. So we know they had the know-how, but did they have the materials? One thing needed in the system that Japan was using was “heavy water.” Heavy water is water made up of isotopes of hydrogen and oxygen. It can be used as a necessary component in nuclear reactors. It is possible that Japan had heavy water.

    Shitagau Noguchi was a Japanese industrialist who had done wonders building power infrastructure and factories in Korea. He produced energy, gunpowder, other chemicals, and heavy water. By April of 1944, he was able to produce approximately 50cc of heavy water a month. He also discovered fields of uranium in Korea. So if the Japanese government was able to get some unrefined uranium and heavy water, they might have had enough for developing in the early stages, but Nishina was desperate for more. The Navy spent a king’s ransom searching for more uranium. Until they got a message from a far-flung ally…

    By the closing days of the war in Europe, Germany was in desperate straits. They were literally surrounded by enemies and there was absolutely no hope for success. Hitler had a huge stockpile of uranium that Germany had been using in their own experiments. The last thing he wanted was for this stockpile to fall in the hands of his enemies. So he loaded the uranium into a submarine and sent it to Japan. This would have given Japan more than enough to complete their program. But, the sub was captured by America, and would ironically be used in the Manhattan Project.

    There were reports and rumors of Japan testing a nuclear weapon as reported by Robert Wilcox in his book Japan’s Secret War: Japan’s Race Against Time to Build Its Own Atomic Bomb. But sadly, there is no conclusive proof of any weapons test, or that Nishina got heavy water from Noguchi’s plants. But why is the evidence so scanty? Even with the government destroying much of the paperwork, there should be more evidence. And what happened to Nishina’s centrifuges?

    The Cover-Up

    After the WWII allied victory, allied leaders discovered Japan’s nuclear program. Throughout the war, scientists had sworn up and down that it was impossible for Japan to develop their own weapons. Here was proof that they were wrong – slapping them in the face. What did they do? They destroyed the entire program. And worked for years with the Japanese government to conceal the program. Why? Why would you work with a former enemy to quash records of a former weapons program? The answer is simple when you have a mutual enemy to whom the information is valuable.

    In the closing months of WWII, it became clear that the USSR was going to be a major force in the world. The USSR’s battles with Hitler’s forces had carved it into the greatest land force in the world. Almost immediately after the use of the atomic bombs on Japan, American leaders began to dread what might happen if this technology were to fall into the hands of the Soviets. After the fall of Germany, the allied governments began “Operation Paperclip,” a program designed to suck up as many of Germany’s top researchers and scientists so that they would not fall into Russia’s grasp.


    So it seems likely that America, fearing the know-how to make nuclear weapons might be known to the USSR, worked with Japan to scrub the record clean. While it might sound preposterous, it is not without historical basis. Unit 731 was a Japanese military research division that conducted truly deplorable and horrifying experiments on prisoner of wars and civilians. But instead of charging them for war crimes, allied leaders pocketed all the research and aided the Japanese government in keeping the horrible deeds of this unit quiet. Once again, because they feared that Russia could gain actionable intelligence from this research.

    So, it is entirely possible that Japan was very near to completing a nuclear weapon, or possibly created one and even tested it. But we may never know the whole truth…

    Where do you point this thing?

    That leaves us with an interesting question. If Japan had been able to complete the bomb before America, would they have used it? If so, where? As for the first question, of course, they most likely would. There is no country faced with an existential threat that would not use nearly every weapon in its arsenal. So, what would be the target? It is hard to imagine Japan striking the American homeland. By the end of the war, Japan had essentially no navy to speak of. Most likely, the target would have been one of the lands occupied by Americans. This would have caused hundreds of thousands of American casualties.

    Would such a strike have been war winning? I can’t say for sure, but because America was developing nuclear weapons as well, it would have been the first time two nuclear powers went head-to-head. The absolute worst case scenario I can imagine is a tit-for-tat nuclear battle. Japan drops an a-bomb on an American staging area, and America responds in kind, then it goes back and forth until both countries go through their supplies and begin to restock. I think that eventually, the outcome would still be a Japanese defeat (or at least an armistice), but with millions more dead.

    In Conclusion

    Japanese people are rightfully proud that their country today has the ability to create nuclear weapons but does not as a matter of policy. But often in the subtext of such a message, America is like the Empire in Star Wars with the Death Star, and Japan is Alderaan. But this entirely ignores the actual historical context. If Alderaan was building their own Death Star to use against the Empire, would it have been so wrong for the Empire to use theirs to neutralize a threat? When it comes to nuclear war, it is hardly as black and white as we would like to imagine it to be.

    I sometimes hear the message from people, “America is the only country evil enough to use a nuclear weapon.” But recent discoveries prove this wrong. Not only was America willing to use nukes, but so was Germany, as was Japan. Japan was not just a victim in the nuclear game, it was a major player. And as the old adage goes, “If you play with fire, you will get burned.”

    Reference: Alkon, P. K. (2006). Winston Churchill’s Imagination. Associated University Presse.
    Reference: Wilcox, R. K. (1995). Japan’s Secret War: Japan’s Race Against Time to Build Its Own Atomic Bomb. Da Capo Press.
    Reference: latimes.com/

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