Piercing the Fog - Air Force Historical Studies Office

Piercing the Fog
Maj. Gen. Clayton L. Bissell
to streamline resulted from the numerous Allied air forces; each was seeking to
complete its mission without much c~ordination.~ The chart on the facing page
illustrates the extent of the complicated air intelligence fuctions that grew over
time in the CBI.
Signal intelligence played a growing part in the CBI fighting, especially
from 1943 on. As in other theaters, SIGINT came in several forms and found
varying uses. MAGIC diplomatic decrypts told the Allies of Japanese intentions
to expand Burma’s railroad system, of the changes in Japanese command, and
of the scheduled movements of divisions to reinforce the front. Knowing the
enemy’s plans was one thing; finding appropriate targets in the jungle and
elsewhere suitable for air attack was a vastly different issue. Regarding target
location, SIGINT was less valuable, so the airmen turned first to HUMINT in
the form of agents able to provide precise data on target locations and types, and
then to follow up with damage assessments. Low-level radio intercepts and
reading of commercial wireless telegraph traffic also indicated how effective air
raids were, not only in and around Rangoon and Bangkok but in the major
Japanese-occupied cities of China as we11.6
Despite the use of SIGINT, operational and tactical air intelligence
collection in the CBI area depended largely upon photoreconnaissance, flight
reports from air crews, and POW interrogations. Agents or contacts in Japaneseoccupied
areas occasionally provided supplemental data, but this source was not
substantial until later in the war. SIGINT assumed greater importance when the
first ULTRA representative, Maj. J.F.B. Runnalls, amved in New Delhi from
Washington on December 19,1943. In Delhi, Runnalls joined a British theater
intelligence organization already engaged in deciphering enemy transmissions,
and he was heavily influenced by England’s experience in Europe and North
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