[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-
Page 65
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)