The recent study of the World War П era Japanese atomic bomb projects. Operation ‘Ni’ and Operation ‘F’, reveals their small scale and the erroneous scientific premises of their leading physicists, Nishina, Yosio and Arakatsu, Bunsaku. Nevertheless, widespread false rumors persist that the Japanese succeeded in developing their own atomic bomb in secret and tested it on the shore of North Korea on 10 August 1945. Indeed, a group within the US Army tried to exaggerate the capabilities of the Japanese atomic bomb projects. In this paper the authors try to shed light on the motivations behind such assertions on the part of the Army cohort and other Americans.