A cryptologic veteran's analysis of "day of deceit"--a book review

Cryptologia, Apr 2000 by Jacobsen, Philip H

The book regurgitates the old and thoroughly repudiated hearsay report of dead Dutch codebreakers' prewar determinations that Japanese carriers were in the North Pacific enroute to Hawaii. Only now it has the Dutch putting them in the Kuriles instead of the North Pacific. The book also repeats Parker's reporting of the tanker Shiriya moving eastward from the Bonin Islands in a 1 December 1941 message (SRN 115398) to Destroyer Division 7 with the Kido Butai that was intercepted on the Tokyo broadcast. Again, it does not tell its readers that this JN-25B message was only decrypted in 1945-46 and translated in 1946-47 and that the raw intercept was enroute to Washington DC in the U. S. postal system on 7 December 1941.

To further its revisionist conspiracy theory, the book argues that government censors are still withholding the publication of decryptions (and translations) of hundreds of vital Japanese naval messages whose secrecy is a part of this monstrous conspiracy. Stinnett points to missing Station Message Serial (SMS) numbers and missing versions of original transmissions by fleet units and commanders (supposedly on high frequency radio) that appear on shore station fleet broadcasts to naval ships and point to point circuits. However, the book does not mention that after the war navy analysts discovered that about 7,000 Japanese naval messages per month were forwarded to Washington from Corregidor, Guam and Hawaii from July to December 1941. During the expanded intercept coverage of WWII, an OP-20-G official estimated that the U. S. intercepted 60 percent of Japanese naval traffic. Therefore, far more than 10,000 messages were probably sent over the airways by the Japanese Navy per month in the months before Pearl Harbor and less than 60 percent were actually intercepted. Thus, the missing SMS numbers and original transmissions could be accounted for by missed intercepts and transmissions originated by land-line, cable, visual means or even hand carried to shore radio stations. In fact, there was a cable office at Hitokappu Wan available to fleet units to send messages to Tokyo without transmitting on high frequency radio.

Again, in 1945-46 analysts decrypted those intercepts from the Pacific that were available in Washington. A total of 26,581 messages in seven different crypto systems were intercepted between 5 September and 4 December 1941. Between 15 March 1946 to 20 August 1947, OP-20-G analysts and linguists from ONI undertook the study of these 26,581 post war decrypts and only 2,413 were considered important enough for full translations. Of these, only 188 were isolated as pertaining specifically to the events of 7 December 1941.1 This information contradicts the book's assertion that government censors are withholding disclosure of hundreds of vital decrypted and translated messages in furtherance of the alleged conspiracy by President Roosevelt and many top and middle level government officials. Those 2,413 messages that were translated in this period are available in the SRN series and no other decrypts or translations are available for this period of time.