Surprised at Tet: U.S. Naval Forces in Vietnam, 1968
by Glenn E. Helm
Reference Librarian, Navy Department Library, Naval Historical Center.
His research interests include intelligence, surprise attack, and the history of
Indochina. He is currently writing a book on the intelligence and operational history of
the Tet Offensive.
Awaking to the sound of explosions, Rear Admiral Kenneth K. Veth,
Commander U.S. Naval Forces Vietnam (COMNAVFORV), moved to the rooftop of his rented house
to witness a dazzling display of rockets and flares lighting the Saigon night sky. All
around, the sound of battle during the early hours of 31 January 1968 heralded the arrival
of the 1968 Tet Offensive. Armed with automatic weapons and hand grenades, the Admiral and
his housemates waited for a ground assault which fortunately never came. During the
remaining hours of darkness, Veth kept informed of events by listening to military police
and other tactical communications on the radio. Since he spent the night on the roof of
his house, he was unable to direct operations from his headquarters.
Despite numerous warnings, the intensity, coordination and timing of the Tet Offensive
surprised the allied intelligence community, including naval Intelligence. In addition to
a flawed intelligence collection effort, naval Intelligence and COMNAVFORV misunderstood
critical information, resulting in American naval forces being improperly deployed and
surprised when Saigon and numerous other targets were attacked on 31 January 1968.
During the Tet truce, Task Force (TF) 117 (Riverine Force) was scheduled to deploy into
western Dinh Tuong and eastern Kien Phong provinces, where it was expected to interdict
intensified enemy resupply efforts. Captain Robert S. Salzer, the commander of the
Riverine Force, later called it a "show and tell" operation, remarking,
"there was no reason whatsoever to be there. We went up there along the skinniest
canal we could, till we ran out of water completely, then we ploughed through the mud
some... Nothing much happened. There was no reason for anything to happen. The
Vietcong were all the way to the east of us by this time. So much for what [American
intelligence] thought they knew." On the morning of 30 January, the task force
received word that the Tet truce was canceled. Offensive operations resumed, but infantry
units remained near canals for rapid redeployment. The situation in the Delta deteriorated
quickly the next morning as enemy forces attacked My Tho, Ben Tre, Cai Lay, Cai Be and
Vinh Long. Salzer recalled: "We began to hear rumors that things weren't going quite
so well in our splendid isolation. Bill Knowlton, who was a brigadier general then flew
in, saying 'My God, it's Pearl Harbor over again.'" A Riverine Army company was
airlifted to Vinh Long to support ARVN forces at 1810 on the 31st. Another company was
flown to reinforce the defenses of the permanent Riverine base at Dong Tam, near My Tho.
During the night, the majority of the task force withdrew to Dong Tam, where they arrived
before dawn despite enemy harassment (including an ineffective ambush). In the fiery glow
of nearby fighting, the Riverine force was resupplied and moved out at daybreak. At 1550
on 1 February, these forces were hurled into battle in My Tho and, subsequently at Vinh
Long and Ben Tre. During the fighting, as normal sources of intelligence temporarily dried
up, the Riverine Force became heavily dependant on Air Force-supplied
radio-direction-finding fixes for information on enemy unit locations. In the end, the
Riverine Task Force was credited with saving the Delta.
In anticipation of increased enemy infiltration of supplies from Cambodia, TF 116 (River
Patrol Force or Game Warden), commanded by Captain Paul N. Gray, had deployed nine PBRs
(patrol boats, river) to the Cambodian border region. Four PBRs were based at the US Army
Special Forces camp at Chau Doc on the upper Bassac River in the northwest of the Mekong
Delta. To the immediate east of Chau Doc, five PBRs were deployed to the Special Forces
camp at Thuong Thoi in Kien Phong Province to patrol the upper Mekong River. The
repositioning of PBRs to Chau Doc may have had little impact on infiltration, but the
vessels proved crucial in repelling a major ground attack on the city during Tet.
Elsewhere during Tet, TF 116 units engaged enemy forces at My Tho, Ben Tre, Vinh Long, Sa
Dec, the Saigon area and the LCU (landing craft, utility) ramp at Hue. Remarking on the
enemy's ability to prepare for these attacks without detection, Captain Gray admitted that
"...I have no concrete knowledge of how such a logistics miracle was accomplished by
the VC in the Delta."
The month of January saw increased patrol activity by Task Force 115 (Coastal Surveillance
or Market Time) as the northeastern monsoon abated. There is no evidence that TF 115,
commanded by Captain R. Dicori, deployed in a different manner than usual as Tet
approached. Even so, a patrol vessel made what might have been one of the first contacts
with enemy forces at the start of the offensive, when it intercepted five or six uniformed
enemy personnel concealed in an unlighted sampan three miles south of Qui Nhon, late in
the evening of 29 January. During Tet, Market Time forces became engaged in a number of
firefights involving sampans and provided naval gunfire support to forces ashore. Harbor
defense patrols (Operation Stable Door) engaged enemy swimmers during the early hours of
31 January but were unable to prevent damage to the bow of the Norwegian tanker Pelican in
Cam Ranh Bay. Despite extensive commitments in support of allied forces ashore during the
Tet fighting, TF 115 thwarted four enemy trawlers at the end of February attempting to
simultaneously infiltrate supplies into the RVN.
The Navy's operating forces in Vietnam relied on COMNAVFORV's intelligence organization,
headed by the Assistant Chief of Staff for Intelligence, Captain Giles C. Upshur, Jr., for
all necessary intelligence on potential friends, enemies and operating areas. The
organization was also responsible for fulfilling intelligence requirements of higher
headquarters and the Defense Intelligence Agency. Each commander subordinate to COMNAVFORV
was responsible for maintaining an intelligence collection organization, and all Navy
personnel were expected to report information of intelligence value. Naval Intelligence
personnel were stationed throughout the RVN, including Coastal Zone and Riverine Area
headquarters, Coastal Surveillance Centers, some PBR bases and some Sector Operations and
Intelligence Centers. An intelligence officer was assigned to the staff of each of the
three Navy task forces. In addition, an intelligence advisor and a counterintelligence
advisor were assigned to the Vietnamese Navy. Naval Intelligence Liaison Officers (NILOs),
tasked with providing intelligence to COMNAVFORV and allied naval forces within their
assigned geographic areas, were stationed in 24 towns and cities, primarily provincial
capitals of coastal and Mekong Delta provinces. No boats or watercraft were assigned to
NAVFORV with the primary purpose of obtaining intelligence.
The task forces played a significant role in the collection of intelligence. For example,
in addition to questioning and detaining Vietnamese nationals, TF 116 inserted Provincial
Reconnaissance Units and Navy SEAL (Sea, Air and Land) teams on intelligence collection
missions. In support of TF 115, naval aircraft conducted patrols along the Vietnamese
coasts. The aircraft detected and photographed merchant shipping, observed patterns of
junk movement, and supported surface units during possible submarine contacts. Relevant
intelligence reports and analysis went to various intelligence consumers. American and
Vietnamese naval intelligence personnel interrogated enemy prisoner and deserters,
exploited documents and materials and produced intelligence.
James C. Graham, a CIA employee who served on the Board of National Estimates, recalled,
"I think that there was an intelligence failure at Tet, but I think it was composed
of many elements... the anatomy of any intelligence failure is always a very complicated
thing." Numerous reasons account for the intelligence failure that led to COMNAVFORV
and his intelligence organization being surprised by the Tet Offensive. The following list
is not exhaustive; it merely provides a basis for understanding the failure. In some
cases, there is strong evidence that a particular factor contributed to the failure, in
other cases the evidence is less clear but highly suggestive nevertheless.
With a limited staff and a lengthy list of collection requirements, NAVFORV intelligence
personnel could expend only a small portion of their efforts seeking evidence of an
unprecedented, coordinated, country-wide attack such as the Tet Offensive. In addition,
U.S. Navy operational forces generally placed a low emphasis on intelligence collection,
and it was only in isolated cases that operational boat skippers were successfully given
intelligence briefs and then meaningfully debriefed after an operation. TF 115 and TF 116
failed to collect data on ports, boat identities, routes, cargoes and personnel. Analysis
of such information would have assisted the Vietnamese government to control water
traffic. Rather than utilizing their special warfare skills for intelligence purposes,
operating forces often misused the SEALS as covert infantry units. Their abilities to
conduct infiltration and reconnaissance, as well as to run agent nets, were often ignored
in the rush to employ them in disrupting and destroying specific enemy targets.
A major problem faced by NAVFORV intelligence was the inability of Allied naval patrol
forces to significantly interdict enemy logistic activity along the rivers and coast of
the RVN, with the likely exception of large vessels approaching from the open sea. As a
result, TF 115, TF 116, and Vietnamese Navy patrols did not obtain evidence of the coming
Tet Offensive. Communist forces, particularly those in the Mekong Delta, utilized the
waterways of the RVN to position personnel and supplies before the offensive. Yet U.S.
Navy coastal and river patrol forces intercepted and captured virtually none of this water
traffic during the several months prior to Tet. Despite a significant increase in boat and
personnel detention in January 1968, NAVFORV captured a mere 22 weapons, 6.5 tons of rice
and no ammunition.
The basic difficulty confronting allied naval forces attempting to interdict the covert
movement of enemy supplies and forces on or across waterways was that patrol forces were
overstretched and sometimes poorly utilized. A study of the Mekong Delta completed in the
summer of 1967 tallied 732 miles of major waterways, exclusive of the Rung Sat mangrove
swamp. Approximately 90 PBRs were available to cover this area, of which a maximum of 30
two-boat units were continuously on patrol. They could not keep all likely areas of enemy
activity under constant surveillance. In practice, PBRs patrolled only those areas of VC
activity identified in regular intelligence reports. An important source of these reports
was aerial surveillance by NILOs who did not have operational control of aircraft, since
they were merely passengers on Army and Air Force planes. Although NAVFORV had a
requirement for daily surveillance, aircraft were typically available only three days per
week and were not equipped for operations at night, the time of most enemy activity.
A March 1967 study determined that PBR tactics (assuming a 10-hour night) included four
hours of drifting with the engine shut down, two hours underway at less than 12 knots, and
4 hours underway at over 12 knots. PBRs could detect sampans at 500-1000 yards with radar
and other equipment, but only at 100-500 yards without it. However, on a quiet night, one
could hear PBRs operating at high speed more than three miles away. SEAL teams conducting
ambushes along rivers frequently reported hearing and seeing enemy signals, presumably
warning of approaching PBRs, as much as 30 minutes before their arrival.
COMNAVFORV knew that communist forces used the waterways in the Third Riverine Area (the
south and southwestern portions of III Corps), including the Nha Be/Saigon, Dong Nai, Vam
Co Tai and Vam Co Dong rivers, for transportation and supply. Allied security in this
area, including the control of river crossing points, varied enormously. In some places,
it was virtually non-existent. For example, the Bo Bo Canal in Long An Province was
particularly well situated for the transport of supplies from communist base areas in
Cambodia. An intelligence advisor remarked that unless allied forces gained control of
these waterways, "they will continue to be used at will by the VC/NVA...they will
remain basic routes for infiltration, supply and crossing points for the VC/NVA." The
Senior Intelligence Advisor in the Third Riverine Area during Tet claimed that Vietnamese
naval forces were too slow and that, "The VC use our rivers at will. To effectively
stop them the Third Riverine needs [US Navy] PBRs, SEALS, and Seawolves [helicopters].
Without the above the VC will continue to run supplies, and troops whenever they
The Fourth Coastal Zone, located along the Cambodian border in the far west of the Mekong
Delta, was an area through which significant amounts of enemy supplies moved from Cambodia
into the RVN. Working together, the NILO at Ha Tien, American advisors, and the Vietnamese
Sub-Sector Chief had developed an agent network capable of providing early warning of
large scale overland movement of supplies, but they could not obtain rapid aerial
photographic reconnaissance to confirm reports of infiltration. Moreover, communication
with the outside remained uncertain due to an inadequately performing generator. The
nearest aircraft were located along the coast at Rach Gia, about 50 miles from the border
and even farther from the RVN island of Phu Quoc, located half-way between mainland RVN
and the Cambodian port of Sihanoukville, through which a great deal of communist supplies
were arriving. Aircraft were only available in the vicinity of Phu Quoc when not needed on
the mainland, and ready reaction to surveillance needs was considered marginal.
Coastal surveillance resulted in relatively few interceptions of enemy personnel and
material. Although this was ascribed at the time to the effectiveness of patrols which
discouraged the enemy, it was more likely due to patrolling inefficiencies. Vietnamese
Navy assets similarly were subject to poor utilization, often being used for base defense
rather than aggressive patrolling. Referring to Coastal Group 12, a Vietnamese Navy unit
in I Corps with responsibility for patrolling lagoons, an American advisor remarked,
"Unfortunately, they perform routine patrols unsatisfactorily in that the junks are
prone to anchor and the crew go to sleep, day or night." A fellow advisor commented
"The attitude [of] `let the Americans do it' prevailed." In all fairness, some
units conducted creditable patrols, but others were judged barely satisfactory and some
were considered totally unacceptable.
The quality of Vietnamese naval units often fluctuated over time, due in large measure to
the attitude of their commanding officers. One advisor remarked that emphasis on numbers
of boardings, inspections and detected contacts reduced the effectiveness of patrols. For
example, one naval unit spent several hours almost daily inspecting a fishing fleet
located 3-4 miles off the coast, in the same place on a regular basis. Enemy units
presumably noticed the pattern and slipped along the coast while the patrol unit was
otherwise occupied. American crews were also affected by pressure to produce results. An
advisor who served in the Mekong Delta observed, "I mean [American PBR crews will]
stop anybody and take in 50 people and call them suspects if they feel that the pressure
is on them to come up with some suspects."
Another factor was the lack of Vietnamese language capability among NAVFORV intelligence
personnel. Few Americans managed to master the Vietnamese language before Tet. In fact,
language training for Navy intelligence personnel remained inadequate until 1970, when the
Navy finally devoted greater resources to the problem. A lack of fluency in Vietnamese
meant that Naval Intelligence personnel were at the mercy of sometimes insincere or even
traitorous Vietnamese personnel. The Intelligence Advisor to the Vietnamese Navy summed up
the need for Vietnamese language training:
"In my opinion it is not sufficient to rely upon the fact that many Vietnamese
officers speak English. Not only are other nationals quite pleased and flattered to find
Americans who speak their language, there are important operational requirements as
well...it would prevent to a greater extent conversations by Vietnamese "around"
the advisor. It is important for Intelligence oriented officers to be fully aware of what
is going on around them and to be able to read newspapers and other printed material to be
fully effective. The lack of these capabilities detracts from the advisory and
One Coastal Surveillance Zone advisor remarked "I don't know if language training
would have been of help, however it might have given me some insight into those I was to
The failure of Navy personnel to understand the Vietnamese language was a component of the
systemic problem of the American effort in Indochina, and one linked to the one-year tour
of duty. In the field, less than six CIA officers at a time together with a small number
of military advisors and intelligence personnel assigned to American units were proficient
in the Vietnamese language.
Poor communication skills and short tours of duty combined with unfortunate results. One
advisor to the Vietnamese Fleet Patrol felt unable to impress upon his Vietnamese
counterpart the potential that his ship had for collecting intelligence. Although American
liaison personnel could only gather a small percentage of available information, he
considered the Vietnamese Navy's ability to "read the people" a potentially
prime source of intelligence. He noted that the Vietnamese Navy could become "more of
an intelligence collection agency and less of an intelligence collation agency if it could
only tap the potential intelligence available through personal contact with millions of
Prior to Tet, allied intelligence failed to recognize changing enemy strategy. Analysts
believed the communists would be foolish to attack urban areas where they would be exposed
to superior allied firepower. The communists would thereby give up their perceived control
over their casualty rate while waiting for the United States support the Republic of
Vietnam to weaken.
Other issues commonly associated with the Tet intelligence debacle such as enemy
deception, enemy indecision, false alerts, analysts' fear of crying wolf, poor information
sharing, and information processing difficulties also contributed to the failure to
provide warning of the upcoming offensive.
Of particular importance to the issue of whether the Navy had sufficient warning of Tet
was all- source intelligence available to Admiral Veth and his intelligence organization
on 27 January. This information painted a dramatic picture of enemy activity and indicated
that a major enemy offensive was imminent. It should have produced a maximum state of
American vigilance as Tet approached. Widespread communist attacks in the northern portion
of the Republic of Vietnam during the night of 29/30 January could have provided 24 hours
warning, yet NAVFORV was still unprepared.
COMNAVFORV and his intelligence organization were surprised by the intensity, coordination
and timing of the Tet Offensive, as evidenced by Admiral Veth's presence at his residence
during the first wave of attacks on Saigon. Of the many factors that led to the
intelligence community's surprise at the offensive, the misguided belief that enemy forces
would not run the risk of attacking the cities and towns of the RVN is paramount. The
belief that an attack during the most important Vietnamese holiday was an almost
unthinkable enemy option was similarly misguided. Had the allied intelligence community
placed greater emphasis on intelligence collection, and acted properly on the intelligence
that they did receive, the Tet Offensive may never have found its way into the history
books as one of the greatest intelligence lapses in the post-World War II era.
For further reading on intelligence and the Tet
Ford, Ronnie E. Tet 1968: Understanding the Surprise. London: Frank Cass, 1995.
Helm, Glenn E. The Tet 1968 Offensive: A Failure of Allied Intelligence. MA thesis. Tempe
AZ: Arizona State University, 1989.
Hoang Ngoc Lung. The General Offensives of 1968-69. Washington: US Army Center of Military
Oberdorfer, Don. Tet. Garden City NY: Doubleday, 1971.
Wirtz, James J. The Tet Offensive: Intelligence Failure in War. Ithaca NY: Cornell
University Press, 1991.
Thanks to Glenn Helm and the Naval Historical
Center for allowing us to post this very informative article regarding the 1968 Tet