対米最終覚書と米大統領の親電の解読工作をめぐる史実の再検証

国際政治研究の先端3

抄録

60 years after the Pacific War, Japanese Foreign Ministry published on October 14 2004 relevant documents related to Japan's Final Memorandum delivered to the U. S. Government at the outbreak of the War. The documents were found in the files of diplomatic archives by the author in 1999. They reveal that the Ministry was supposed to submit to the U. S. Government the Final Memorandum which was originally worded to express an intention to enter into war. This formula was not accepted and the Memorandum was changed to simply inform Japan's intention to terminate the Japan-U. S. negotiations. When Final Memorandum which was divided in fourteen parts was cabled to the Japanese Embassy in Washington, the 14th cable embodying the concluding paragraph was withheld for 15 hours while its phrase underwent subtle wording change. A withholding of cabling the final phrase as well as additional corrigenda for 15 hours caused a fatal delay in transmitting the Memo to the State Department at 1:00 p. m. (Washington time), just before Pearl Harbor attack.
There had been no serious in-depth investigation by the Japanese Government to pursue the reason for suspending the telegram of the 14th part of the Memo at the Tokyo side, and in its stead, a wrong search focused on a confused cable-handling and typing of the Final Memorandum by the Japanese Embassy. The delayed dispatch of final part of the Memo could be traced to an obstruction made at Tokyo Central Telegraph Office on the same day in connection with a clandestine army operation carried on by Major Tomura of Communication Section of Japanese Army's General Command when they withheld for ten hours the American President's message to the Emperor. During the seizure of Roosevelt's message, it is conclusively analyzed that a secret decoding was done by the Army before its delivery to the U. S. Embassy at 10: p. m. on December 7 (Japanese time). Major Tomura admitted later that he feared the Emperor might be induced to accommodate the President's appeal to delay the war. This Paper examines that the Foreign Ministry must have been informed of the decoding, and therefore, it had to adjust the wording of the last paragraph of the Final Memo to respond to the final position of the U. S. Government. Also a cover-up of delayed dispatch of correcting cables to Washington was made to block reinvestigation up till now.
Author observes that President's Message intended to delay war with Japan since he preferred to fight with Hitler first. Roosevelt opted for a last-minute attempt to send his Message directly to the Emperor to avoid war, as suggested by the Japanese Embassy.