[143]      COMMUNICATION INTELLIGENCE SUMMARY, 7 November, 1941
 
General.-Volume of intercepted traffic larger than usual. Due to the use  of the general call "All Major Force Flags" on the UTU for delivery to  all Combined Fleet units, affiliation of unidentified calls with forces  to which at-
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tached is very difficult. Use of large number of alternate calls for  major fleet forces, many of which have not yet been definitely  identified or associated with known calls, renders the picture more  confusing. Appearance of the prefix "JITSU" (authenticator for bona fide  traffic) in several messages indicates that a communication drill is  being held but without indication as to what units are participating and  therefore much of the traffic is suspected of being "drill."  Jaluit  Radio is handling traffic direct with Yokosuka Radio probably due to  congestion of Mandate circuits from the Marshalls caused by heavy  concentrations in that area.
Air.-Continued high traffic level for all classes of air activities,  mainly centered in the Taiwan area, but also with all air activities in  the Mandates included in headings of messages. Dispatches originated by  Fourth Fleet Command included Air Forces, Base Forces, Air Stations, and  all types of Mandate activities in long headings.
Fleet.-Fourth Fleet Command remains in Truk area. There are indications  that portions of the First Fleet may be moving to the Takao area but  identifications are not sufficiently certain to confirm this.
Greatest effort is being made to increase the number of identified calls  to facilitate analysis of the traffic but Orange changes in methods of  handling fleet traffic renders this more difficult than had been hoped.

 

(FROM: U.S. CONGRESS JOINT COMMITTEE ON PEARL HARBOR ATTACK HEARINGS; PT.  35, THE CLAUSEN INVESTIGATION, PP. 62-81. EXHIBIT "A" DAILY COMMUNICATION INTELLIGENCE SUMMARIES)