spartans_in_darkness

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force surrounding them."" Whether this was
marine bravado or Colonel Lownds truly missed
the significance of the intelligence, especially the
SIGINT, is unclear. However, that same day,
the marines picked up a rallier from the PAVN
forces who told them that he was from the 325C
Division and that they were going to attack that
night.'"
(D) Early in the morning of 21 January, battalions
from the 95th Regiment of the PAVN
325C Division attacked Hills 861 and 881 northwest
of the marine base. After heavy fighting, the
Vietnamese were driven off. To the south, another
PAVN battalion overran Khe Sanh village, severing
Route 9 to the west of the base. The main
ammunition and fuel dumps on the marine base
were detonated by PAVN artillery rounds.
Suddenly, the marines were in a fight and short of
supplies.
(D) In reaction to Davidson's earlier report of
the critical situation at Khe Sanh, General
Westmoreland ordered the formation of a special
command post, MACV-FWD, under the command
of his deputy, Lieutenant General
Creighton W. Abrams.'' Another marine battalion
was flown in to reinforce the garrison which
now numbered nearly 6,000 marines, U.S.
Special Forces, and ARVNrangers. An airlift was
started to resupply the marines. Air Force cargo
planes flew in 130 tons of supplies, often under
mortar and machine gun fire. Also arriving with
the supplies were SIGINT reinforcements.
(S//Sf) There had been a small SIGINT support
detachment (DSN-414J4) at Khe Sanh since
August 1967.A team of morse intercept operators
and analysts had supported the marines ever
since. Usually numbering anywhere between
fourteen and twenty-five personnel, they manned
three morse intercept positions, one COMSEC
monitoring post, and an ARDF liaison position.
The team had supported two extra SRDF positions
on hills to the south of the base, but after the
initial skirmishes in early January, these teams
had been withdrawn to the main base.'!"
(sl/Sn Just before the siege began in earnest
on 21 January, the detachment had monitored
tactical voice communications among the communist
units surrounding Khe Sanh. At first, the
marines in the base taped the transmissions and
shipped them to its headquarters unit at Danang
(USN-414J) for processing. But once the fighting
started, this procedure proved to be tactically useless
to Colonel Lownds' command. So, on 22
January Danang flew in a Vietnamese language
voice exploitation team. The next day an NSA
civilian Vietnamese linguist,1
I
arrived along with extra intercept equipment and
tape recorders for the voice effort.i'" P. L. 86-3 6
(S//Sf) Shortly after voice intercept operations
started, Colonel Lownds informed the
marines that he was receiving basically the same
intercept from a South Vietnamese detachment of
six voice intercept operators under a Captain Phat
supporting the ARVN 37th Ranger Battalion also
defending Khe Sanh. The marine voice intercept
team moved into the ARVN bunker and divided
up the functions with the Vietnamese. The ARVN
would intercept the PAVN voice transmissions
and transcribe them. The marines would translate
the scripts into English and pass important
intelligence to the marine commander.
(S//Sf) The voice intercept team concentrated
on the communist artillery nets which provided
information on their general firing plans and,
occasionally, the actual order to fire on the base.
The combined team was able to tip off the command
bunker which, in turn, could warn the
marines to take cover. Later on in the siege, the
team monitored plans for night probes against
various positions for purposes of reconnaissance
and assaults in force. It has been reported that
upwards of 90 percent of these probes were
tipped off in advance thanks to the voice intercepts.Y'"
This figure is difficult to evaluate
because the marines utilized a number of other
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