McNair Paper Number 41, Radical Responses to Radical Regimes: Evaluating Preemptive Counter-Proliferation, May 1995

Japan's scientific community was also aware of the explosive possibilities of an uranium bomb. During World War II, the Japanese Army funded one nuclear research project in Tokyo and the Japanese Navy started two other such projects.

The lieutenant general who ran the Aviation Technology Research Institute of the Imperial Japanese Army, Takeo Yasuda, followed the scientific literature on the potential for large energy releases due to nuclear fission, and ordered the first study of the subject in April 1940 in Japan. (Note 29) Yasuda passed this mission on to the Japanese Physical and Chemical Research Institute that, in turn, gave the assignment to Japan's leading nuclear physicist, Yoshio Nishina who had previously worked with Niels Bohr in Copenhagen. Nishina worked on this problem at his research institute, the Riken, equipped with a small staff, a small cyclotron, and marginal funding beginning in April 1941. (Note 30)

In the Spring of 1942, the Japanese Navy began its first of two parallel research projects. The Japanese Naval Technological Research Institute convened a group of outstanding scientists to look into the feasibility of a Japanese atomic bomb. (Note 31) After ten meetings, this scientific panel concluded that "a bomb would necessitate locating, mining and processing hundreds of tons of uranium ore and ...U235 separation would require a tenth of the annual Japanese electrical capacity and half the nation's copper output." (Note 32) They decided the bomb was feasible, but could not be built by Japan before the war's likely end. The Japanese Navy therefore dropped the project on March 6, 1943.

The Japanese Imperial Army project under Dr. Nishina continued however, and was later supplemented by the Imperial Navy's second nuclear program, this one financed by the Fleet Administration Center. The Navy contract was awarded to the University of Kyoto where a second cyclotron was built and operated by Dr. Arakatsu. (Note 33) Each of these Japanese nuclear weapons research projects were underfunded and ran into significant experimental problems. Indeed, Japan was still not very close to a nuclear weapon at the end of the war.

Allied bombs destroyed Nishina's cyclotron on Friday the 13th of April, 1945, terminating Japan's most advanced nuclear research project. (Note 34)

There is some evidence that Germany and Japan were beginning to collaborate at the end of World War II on missile and radiological weapons. One historian wrote that "On or about 17 May 1945 ... a German U-boat commander accede(d) to the Allied directive to surrender, (and) presented the United States with both the documentary and the physical evidence not only that the Nazi Government had achieved a nuclear reactor, but that they had used it to produce radiological weapons which they proposed should be introduced into the conflict by Japan. (Note 35)

The German transport submarine reportedly carried Acharts, aviation material and information headed for Japan for the purposes of aiding Japan's air war with rocket and jet engines and other German V-type bombs." (Note 36)

In addition, and more chilling, the German transport submarine also carried 550 kilograms of unspecified uranium. (Note 37) This led the historian, Geoffrey Brooks, to speculate that it might have been for conversion into Japanese radiological weapons, to be used like a chemical munition, capable of spreading radioactive dust over the the batllefield and with the potential to destroy "a number of major cities, condemning millions of men, women, and children to death by radiation sickness or from lethal cancers contracted by the spread of the material." (Note 38)