I recently learned from Donald Keene's diary translations (see also here) that Japanese modernizers had been worried about the Russian threat since the Meiji era.
Dyson also has some interesting comments about space exploration and genomics immediately following the discussion about nuclear weapons. I almost skipped listening to this interview, having spent several hours with him relatively recently. But someone as knowledgeable and brilliant as Dyson will always generate surprising insights.
Hasegawa's book: Racing the Enemy: Stalin, Truman, and the Surrender of Japan
Summary: ... According to Hasegawa, Japanese leaders' diaries and testimonies suggest that the imminent Soviet invasion was more influential in compelling them to accept the Potsdam conditions. Although Emperor Hirohito's desire to end the war became more urgent after Hiroshima, only on August 9 after the Soviet declaration of war did he clearly say that "it is necessary to study and decide on the termination of the war" . The other peace advocates in the Foreign Ministry on the same day began to urge acceptance of the Potsdam ultimatum . The reactions of the more hawkish military officials seem to have been similar. Both Admiral Toyoda and Army Deputy Chief of Staff Kawabe were surprised at the news of Hiroshima but were not ready to temper their views on continuing the war . Many military officials hoped to mount a final defense, but had counted on Soviet neutrality in order to do so . The Soviet declaration of war destroyed those hopes, and severely weakened the war faction's leverage within the government.
The major strength of Hasegawa's work, and one reason for its new arguments, is its in-depth analysis of Japanese primary sources. Few previous historians in the US had consulted the personal writings of figures like Toyoda, Kawabe, and Tanemura. But Hasegawa also makes more extensive use of Allied primary sources, including the memoirs and diaries of Truman, Byrnes, Brown, and others, which play a key role in his argument about the intent of the Potsdam Proclamation. Hasegawa's careful scholarship has significantly enriched our understanding of the intentions behind the demand for "unconditional surrender," as well as the dynamics behind the Japanese decision to surrender.
I recently had a memorable conversation with a colleague (another former Junior Fellow) who is a professor in the history department. Despite early evidence of talent in mathematics, he decided to study history because he wanted a career in which his abilities would continue to grow and deepen well into maturity. He preferred to reach the peak of his powers late in life, rather than suffer the continuous decline so dreaded by precocious young geniuses in theoretical subjects. I begin to see his point.