The "Strategy" Entrusted to Balloons: Balloon Bombs and the Invisible Defense of Japan and the U.S.S.R. - Early 1940s

The "Strategy" Entrusted to Balloons: Balloon Bombs and the Invisible Defense of Japan and the U.S.S.R. - Early 1940s

In 1944, as the situation in the Pacific War began to worsen, the Japanese Army devised a plan to use the prevailing westerly winds to create a "balloon bomb. The idea was to suspend a bomb from a giant paper balloon and use the wind to attack the U.S. mainland. The development was carried out in secret, and the balloons were released mainly from the coastal areas of Ibaraki and Fukushima prefectures. In total, more than 10,000 bombs were released, some of which actually crossed the Pacific Ocean and reached the western United States. Wildfires and a few human casualties were also reported, but the U.S. government kept the news from the public in order to avoid public anxiety. On the other hand, the U.S. government did its utmost to analyze the arriving balloons and build an interception system.

The manufacturing process of the balloon bombs utilized unique Japanese technology. The balloons were made by pasting together layers of Japanese paper, and the glue used to adhere the paper was extremely adhesive. After the war, American researchers tried to determine the identity of the glue, but for a long time it was unknown. In fact, the glue was a natural material made from "konjac," which was processed from the mucilage extracted from konjac potatoes. Although konjac is known as an everyday foodstuff, Japan at that time converted its viscosity into a military material, surprising the American technicians.

In addition, the U.S. intelligence analysis capability showed unusual accuracy in this one case. They collected trace amounts of soil attached to the balloon portion of the fallen balloon and attempted to determine the launch point based on the mineral composition and microorganisms contained therein, as well as the type of pollen present. As a result, the balloons were presumed to have been released from a specific area on the Japanese mainland, such as the coast of Ibaraki Prefecture, and the U.S. identified that point as the target of a future air raid. This is regarded as an early example of sophisticated geological analysis that can be used in modern forensic science investigations.

Even more shocking is the fact that the idea of "carrying germs" in the balloon bombs was being considered in Japan. Some in the Army had proposed using anthrax or plague bacillus as a biological weapon to be mounted on balloons and used to release pathogens on the U.S. mainland. This was backed by germ weapons that had been developed and cultivated by Unit 731 and others. However, this plan was cancelled due to strong opposition from some military doctors and researchers. The reasons were based on ethical considerations, such as the fear of retaliation and the inhumanity of indiscriminately killing and injuring civilians. Implicit in this background was the later historical reflection that Japan did not have atomic bombs and that if it had had nuclear weapons, they might not have been dropped.

The paper balloons carried on the wind were entrusted with Japanese technology, ethics, information, despair, and even pride. Behind the invisible offensive and defense, the wisdom and conflicts of a nation on the verge of defeat were quietly but surely floating in the air.