spartans_in_darkness

"f6P SEeRETNeOMINf....*1
EO 1.4. (c)
(TS//SI):
L...-__---I1What little the U.S. knew came from
two sources. The first was from intercept of DRV
military communications, which contained
targeting, tracking, and warning information
that American cryptologists inferred was
obtained most likely by monitoring U.S. communications."
The second source was interrogations
of captured PAVN and Viet Cong COMINT
personnel.
(TS//SI) In the south, most of what could be
learned about communist signals intelligence
----Lr_..
(V) North Vietnamese intercept operator Cit work
(Captured Photoqraph)
activities came from two/sources. The first was
from the intercept of Viet Cong military, NLF, or
PAVN communications. This effort collected only
fragmentary information which was usually just
scattered references to ARVN or U.S. military
communications/being monitored. Generally, it
was difficult to/isolate communist SIGINT-related
communications. This was so for two reasons.
First, their messages were included in the general
intelligence traffic passed by communist military
intelligence sections attached to combat unit
headquarters staffs. Second, the communist tactical
COMINT units, known as Technical Research
Units (TRU), as a standard procedure, were located
physically close to their host unit headquarters
so that the intelligence they provided was often
hand carried or transmitted by landline.Y'
('fS//SI) Like information about Hanoi's
COf\lINT effort, the overwhelming majority of
intelligence about southern communist COMINT
came from POW interrogation, captured documents,
and the rare capture of an intact enemy
COMINT unit, as was the case with Project
Touchdown in 1969. What Touchdown revealed
was a shock to American COMSEC specialists,
both in terms of what American communicators
were saying and what the capabilities were of the
average communist TRU. 9 4
('fS//SI) American thirst for knowledge
of communist signals intelligence
was driven largely by the needs of the U.S.
COMSEC program in Vietnam. Almost
from the beginning of the ASA arrival,
there had been an informal COMSEC
monitoring and support mission. By
October 1961, a dedicated ASA COMSEC
unit had arrived at Tan Son Nhut and
assumed responsibility for both the chief,
USMAAG and the Republic of Vietnam
Armed Forces (RVNAF).95 Soon, all three
military cryptologic services had COM-
SEC elements in country, monitoring
their own and selected Allied communications.
Their programs revealed that
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