AN EVALUATION OF THE EFFECTS OF BOMBING ON INFILTRATION INTO SOUTH VIETNAM

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78T02095R000700080097-2
• Release Decision: RIPPUB
• Original Classification: T
• Document Page Count: 29
• Document Creation Date: December 22, 2016
• Document Release Date: August 11, 2009
• Sequence Number: 97
• Publication Date: March 9, 1967
• Content Type: IM

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Top Secret
DIRECTORATE OF
INTELLIGENCE
L06 rlpv/.L)
Intelligence Memorandum
An Evaluation of the Effects of Bombing
on Infiltration Into South Vietnam
ARMY
review(s)
completed.
NSA review completed
Top Secret
10
9 March 1967
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CENTRAL INTELLIGENCE AGENCY
Directorate of Intelligence
9 March 1967
An Evaluation of the Effects of Bombing on Infiltration
Into South Vietnam
SUMMARY
There has been no confirmation of the infiltration
of any North Vietnamese infantry regiments into South
Vietnam since August 1966 although smaller units have
infiltrated. Continuing signs of intensive activity both
in the Laotian infiltration system and in the DMZ,how-
ever, continue to be noted. During the first eight
months of 1966 some 12 North Vietnamese infantry regi-
ments were detected entering South Vietnam, nine through
Laos and three full regiments and elements of a fourth
through the DMZ. Reports of support elements and groups
of filler and replacement personnel moving down these
routes since August are still being received, however,
indicating that the trails are open and active.
The US interdiction program has clearly made the
movement of personnel from North Vietnam into South
Vietnam more hazardous, but there is no good evidence
that it is responsible for the drop-off in the infil-
tration of infantry regiments. The decline appears to
have been based on Hanoi's assessment of its needs in
the South more than on the dangers encountered by the
men on their way to the battlefield.
NOTE: This memorandum was produced solely by CIA.
It was prepared jointly by the Office of Current
Intelligence, the Office of Research and
Reports, and the Director's Special Adviser
on Vietnamese Affairs.
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Information on the infiltration of support
elements, fillers, and replacements is hard to acquire
because on arrival in South Vietnam these personnel
are dispersed among already existing units and the
chances of picking up several members from any one group
are thus reduced. Nonetheless, since July 1966, some
50 such groups have been reported infiltrating South
Vietnam. Of that number, 16 are reported to have come
through Laos, seven through the DMZ, and the others
by unknown routes.
The decision taken by Hanoi in mid-1966 to move
infantry regiments for the first time directly across
the DMZ appears to have been based on North Vietnam's
intention to stage a military operation in northern
Quang Tri Province. There is no evidence that any
unit which moved across the DMZ has gone farther South
than the northern Quang Tri area. Currently, there
are some unconfirmed indications that regimental size
units may have moved across the DMZ in recent weeks
but these may well represent the redeployment of
regiments which moved across originally. All but a
few elements of these regiments were withdrawn into
or north of the DMZ after being hit by US forces
shortly after they first moved into South Vietnam.
Interrogations of captured infiltrators reveals
that the individual North Vietnamese soldier is keenly
aware of the dangers he faces from US air strikes
from the moment he begins his trek to South Vietnam.
Tensions caused by the threat of bombing, the incon-
venience and delay of traveling bomb-ravaged trans-
portation routes, and the need to maintain strict
march discipline all add to the over-all hardships
imposed on infiltrating groups.
At the same time, there are few good reports of
US air strikes causing casualties among the infiltrat-
ing groups. The major difficulties faced along the
infiltration route are sickness, poor food and the
rugged march itself. Captured diaries of infiltrators
and prisoners who have been interrogated have provided
numerous details on the rigors of the trip south.
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The amount of truck traffic observed moving
from North Vietnam toward Laos since October 1966
indicates that, despite the US bombings, the North
Vietnamese will probably again increase the volume
of supplies moved south through the panhandle as they
did in 1965. The flow of supplies began earlier in
the fall of 1966 than it did in 1965 and larger
trucks are being used. Probably 20 percent of the
supplies moving in Laos are lost in transit or to
air attack. Despite this fact, the external logistic
support needed to maintain the expanded Communist
force level in South Vietnam has been adequate. The
flow of supplies through Laos to the border of South
Vietnam in 1966 was almost eight times the level in
1965.
The North Vietnamese were also able during 1966
to improve existing supply networks and to complete
significant amounts of new road construction. The
road network through Laos, for example, was expanded
from about 150 miles at the start of the bombings to
650 miles at the end of 1966. These developments
have been made at high cost in terms both of labor
diverted to offset the effects of the air strikes
and in terms of the material resources of North
Vietnam. The cost of the damage to transport fa-
cilities and equipment alone ranges from $65 to $70
million.
25X1
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I. RECENT PERSONNEL INFILTRATION
The infiltration of almost 80,000 North Vietnam-
ese into South Vietnam during 1966 had been accounted for
in MACV statistics as of 8 March 1967. Some 40,000
of these are listed as "confirmed" and another 10,400
as "probable." The remaining 29,000 are listed in
the "possible" category. There are a few reports of
infiltration already in 1967. Information on 700 of
these already has proven firm enough to warrant in-
clusion in.MACV statistics. All are carried in the
possible category.
At least 21,000 of the confirmed and probable in-
filtrators in 1966 came in as members of twelve North
Vietnamese infantry regiments. The rest were in
various support elements and other units used largely
as fillers and replacements for units already in place
in South Vietnam. Of the twelve confirmed infantry
regiments, nine came in by foot over trails through
Laos. They took up positions in various parts of South
Vietnam ranging from I Corps in the north down to
parts of III Corps north of Saigon. All of these regi-
ments arrived in South Vietnam by July 1966. Since
that date, the infiltration of three additional regi-
mental-size units has been reported, all in 1966,
but there is insufficient evidence to determine their
infiltration rou.tes..'Allthree are now carried in the
possible category. Three full infantry regiments and
elements of a fourth came by foot directly across the
Demilitarized Zone (DMZ) into the northern part of
Quang Tri Province between June and August 1966.
This was the first time that infantry regiments had
been detected moving directly across the,,DMZ'into
South Vietnam. Previously, all known infiltration of
regular infantry units had taken place over the
traditional Laotian trail system. None of the units
which came across the DMZ is known to have moved
farther south than the northern part of Quang Tri Prov-
ince. No additional infantry regiments have been
listed in either the confirmed or probable cate-
gories as entering South Vietnam across the DMZ
since August 1966.
It is clear thatthe North Vietnamese have not
attempted to maintain ,~ri even flow of personnel to
South Vietnam, but instead have put in men as needed.
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Infiltration figures, however, are often expressed
in terms of monthly averages which tend to be mislead-
ing because the actual level of infiltration varies
markedly from month to month. For example, the
monthly average of confirmed and probable infiltra-
tion for entire year of 1966 is 4,200. The average
for the first six months of 1966--when the bulk of
the infiltration for that year occurred--is 7,000.
The actual figures, month by month, however, are:
January
- 5,300
July
4,300
February
- 9,100
August -
2,000
March
- 12,800
September -
1,400
April
- 500
October -
600
May
- 3,300
November -
--
June
- 11,100
December -
--
Similar dips and peaks have been noted in previous years.
Although the US interdiction program has undoubt-
edly made infiltration a more hazardous undertaking,
there is no good evidence that this program has been
responsible for the drop-off in the infiltration of
infantry. regiments. Evidence on other units, such
as support elements and filler and replacement groups
has been reliable enough to be included in MACV's in-
filtration statistics. Such units have infiltrated
into South Vietnam both through Laos and the DMZ since
August, indicating that these trails are still being
used. Since July 1966, a total of 50 groups of in-
filtrators have been included in the MACV statisti-
cal accounts. Of these, 16 are reported to have come
through Laos, seven through the DMZ, and the routes
taken by the rest are unknown. The infiltration of
filler and replacement personnel is harder to confirm
than that of infantry regiments, because the former
are dispersed among already existing units once they
arrive in the South, and the chances of capturing
several members of such infiltration groups are reduced.
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There is also evidence
from SIGINT and aerial photography that the North
Vietnamese are expanding their infiltration logistics
system in the southern Laos, northern Cambodia areas.
Thus, although there is no firm evidence of the con-
tinued infiltration of infantry regiments through
Laos or the DMZ, there is considerable evidence that
other types of infiltrators and supplies are coming
through.
The most valid explanation of the drop-off in
the infiltration of infantry regiments through Laos
in mid-1966 is that in Hanoi's eyes, there was no
advantage to be gained in the further input of addi-
tional large infantry units. The North Vietnamese
may have reached the force level in the South by
mid-1966 that they had planned and thus needed no ad-
ditional units, at least in the parts of South Viet-
nam serviced by the Laotian trail system.
The input of infantry units across the DMZ ap-
pears to have been an entirely distinct operation from
the normal infiltration through Laos. Initially, at
least, it was mainly intended to pose a serious threat
to the allied position in northern South Vietnam,
thus tying down large numbers of allied troops. The
Communists may also have hoped eventually to open a
link with the infiltration routes through the central
highlands of South Vietnam.
There was fairly good evidence that the North
Vietnamese planned a series of large-scale operations
in Quang Tri and possibly Thua Thien Province in
late 1966. There was almost no Allied deterrent
force along the DMZ and the North Vietnamese appar-
ently believed it would be a simple matter to pump
in at least one division quickly. SIGINT suggested
that at least one other division was programmed to
be sent across the DMZ later. The quick and success-
ful response by US forces to the move across the
DMZ thwarted the Communist attempt for the time being
and all but two to three battalions and some intelli-
gence units of the North Vietnamese forces were with-
drawn into or north of the DMZ.
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The situation in the DMZ - Quang Tri area has
remained generally the same since mid-1966 with
units of the North Vietnamese regiments which first
entered South Vietnam across the DMZ in June-August
1966 moving back and forth from time to time. There
is as yet no firm evidence that the current flare-up
in activity south of the DMZ represents the movement
of any regimental units not previously detected in
South Vietnam.
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II. THE DISRUPTIVE EFFECTS OF THE INTERDICTION
CAMPAIGNS
Based upon a .Limited number of interrogation
reports, the individual North. Vietnamese soldier is
keenly aware of the danger of US air attacks from the
moment he begins his trek to South Vietnam. Tensions
caused by the threat of bombing, the inconvenience
and delay of traveling bomb-ravaged transportation
routes, and the need to maintain strict march disci-
pline all add to the over-all hardships imposed on the
infiltrating troops. At the same time, there are few
reports of US air strikes causing casualties. The
major hardships faced by the infiltrating troops are
the long two to three month march over rugged terrain,
aggravated by poor food, inadequate medical attention,
and homesickness.
The following incidents, gleaned from captured
documents and interrogation reports, typify the dis-
ruptive effects the interdiction program has had on
the infiltration of men and supplies into South Vietnam.
1. During 1965 and 1966 the bombing in Laos
has damaged or destroyed several thousand trucks. A
description of these attacks on the trucks and some
of the problems for truck traffic created by the
bombing has been obtained from a Pathet Lao defector,
that had. been destroyed or damaged, and saw one truck
park that had about 75 destroyed trucks in it. (Con-
tinuous examination of photography of Routes 92 and
96 indicated that numerous trucks were destroyed
along these routes, but possibly not over 100). The
defector said that on a 56-day round trip from Sepone
to Southern Laos his 3-truck southbound convoy had
been attacked 3 times and finally two of the trucks
were destroyed. He was under attack by air. 7 times
in about 4 months, the last 4 times while in a north-
bound convoy in which 9 trucks were destroyed and his
truck damaged. He also said he never saw a plane
shot down.
2. To avoid being bombed by enemy airplanes,
the train stopped and the battalion -took a rest in a
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State-owned farm which was 500 meters northwest of
Dong Diao Station.
they continued their trip taking Route 1. They
walked in Than Hoa Province and thenceforth moved at
night and rested in daytime to avoid enemy airplanes.
3. they took a special train
from the Dong Van Railway Station to the bridgehead
of Ninh Binh Province. At this spot, they were obliged
to cross the river with ferry boats because of the
demolition of this bridge due to US-Vietnamese air
strikes. From Do Lon Bridge to the (Southern) terminal
station of North Vietnam they were obliged to move at
nighttime because of the US-Vietnamese air strikes. It
was known that almost all bridges from Do Lon throug?.a
Nghe An, Ha Tinh, Quang Binh Provinces were bombed. The
two arch bridges were entirely destroyed, but the others
were moderately damaged by the air strikes. They became
unuseable for vehicles but men could cross. In the case
of a fallen bridge, the group was moved across by the VC
local agency in junks.
4. During their infiltration, the troops en-
countered many hardships beyond imagination. The
portion of the route from Than Hoa, especially the
ferry boat crossings, were always threatened by sudden
air strikes of the US-ARVN Air Forces.
5. The local residents appeared to be anxious
about aircraft bombings when the infiltration group
asked them to provide temporary lodging. They were
particularly concerned about the reconnaissance capa-
bility of US aircraft.
6. During the first 10 days all the infiltrat-
ing soldiers appeared to be very eager, but later due
to the long route which they had to walk for almost 2
months, they were tired and discouraged. Since the
time they had to climb mountain 1001, they became more
confused.
7. Quynh Di Village was hit several times.
The target was a bridge where Route 1 crosses a river.
Thirty persons were killed during one raid. A bridge
near Quynh Vinh was destroyed in March 1965. A bridge
near Quynh Ngia was hit twice and completely destroyed.
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Quynh Son was hit repeatedly. Targets were a railroad
bridge and warehouses which were destroyed. River
traffic in the Anh Son District had been hit continu-
ously and greatly hampered. Bombings are seriously
disrupting road and river traffic. All bridges on
Route 12 had been destroyed by October 1965. They had
been replaced by underwater causeways for foot and
vehicular traffic. Truck traffic in October 1965 was
very light (many nights no trucks passed the troops
at all) and always at night. All prisoners have seen
leaflet drops but most were afraid to read them since
it is forbidden. Most prisoners said that people real-
ize aircraft seek only military targets but are afraid
of being bombed by mistake.
8. When I came South, the Do Lon Bridge, the
Hoang Mai Bridge, the Con Ho Bridge and Station I,
which is called the initial station on the SVN infil-
tration route, were all completely destroyed. The ma-
jority of the bombings in North Vietnam have been on
bridges, military barracks and a few factories, and
most of the bombing has been from Thanh Hoa down to
the 17th parallel.
During stops,
the only security posted were 3 men to listen for
the approach of aircraft. Even this was not much of
a threat on the trail in Laos due to the dense jungle
canopy. Shelters and fighting holes were never pre-
pared during these stops.
10. On the way (infiltration into Pleiku Prov-
ince) there were airplanes above but there were no at-
tacks or bombings. All members were disguised with
leaves. When airplanes appeared they moved to the
left or to the right of the trail, or remained still
under tree cover, depending on the orders of the Com-
pany Command Staff. They were not protected by any
AA company. The platoons in the front and rear had
to assign two squads to guard duty to report to the
Company Command Staff if anything was going on around
them.
11. They allegedly infiltrated into Pleiku
Province from Cambodia to prepare for a large opera-
tion; however, when they arrived in the RVN they were
II-3
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bombarded by many aircraft. The air strike. resulted
in a large number of soldiers killed and wounded and
forced the unit to disperse and retreat over a wide
area. As a consequence, the five soldiers did not
know the location or status of their scattered unit.
Other Personal Experiences of Infiltrators
One prisoner reported that his unit could
not use the main roads in North Vietnam for fear of
air attack. The unit had to move over foot paths
or slosh through paddy fields; the going was slow,
and many soldiers suffered from swollen feet. An-
other prisoner noted that frequent air attacks along
the infiltration corridor "disturbed and discouraged"
his unit, and that its "combat capacity had been
reduced" by the time it arrived in the south.
A particularly graphic picture of the effects
of bombing on infiltration was contained in the diary
of a North Vietnamese Army soldier, who
marched south last yea Durin a six-week trek down
25X1 the Ho Chi Minh Trail, referred to air
activity twenty-one times. His unit was struck twice,
and raids hit nearby on four other occasions. Some-
times, he said, the drone of planes could be heard all
day. His unit usually had to move at night without
lights. As a result, men stumbled and fell, injuring
themselves, and often had to eat uncooked food. Once
he broke regulations and lit a fire; this brought a
reconnaissance plane which zoomed overhead at such a
low altitude it "made his hair stand on end." When
his unit arrived in the South, it was substantially
depleted; it had suffered several casualties enroute,
and many others had deserted. Many of the survivors
had malaria; all were exhausted.
Another unit which came south shortly after
25X1 that of had a similar experience. A
diarist from this unit complained of hunger and weari-
ness and mentioned deaths from malaria and bombs dur-
ing the trek.
Because of the fragmentary evidence, it is not
possible to develop a firm estimate of the number of
infiltrators lost on the march south, but the stories
and attitudes expressed above are Dot unusual. Some
prisoners have stated that their units lost as many as
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40 percent of their numbers because of the hardships
of the journey, including disease, shortages of food
and medicine, fatigue, and losses from air attacks.
Aside from losses inflicted directly by air attacks,
those resulting from disease and malnutrition are in
part attributable to the disruption of supply movements
and relay stations caused by the bombing.
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III. THE INFILTRATION OF SUPPLIES
Truck Traffic in the Laotian Panhandle
Truck traffic observed moving from North
Vietnam toward Laos during the current dry season
(October 1966-June 1967) indicates that despite the
bombing, the Communists will probably again increase
the volume of supplies moved south through the Pan-
handle as they did last year. The major traffic
movements this year appear to be on two routes (Route
15 through the Mu. Gia Pass and Route 912) and are
not confined to Route 15 as they were during pre-
vious years. The flow of supplies began earlier
this year than it did last year and larger trucks
are being used.
The total level of traffic moving into Laos
this dry season cannot be estimated because observa-
.tion of traffic on Route 912 has not been available
since 22 October 1966. Truck traffic on the older
route through Mu Gia Pass has averaged 23 trucks per
day on"days of observation since early October 1966
through 21 February 1967. (See Table 1.) If the
very large number of trucks that moved south during
the TET truce period are omitted, the traffic
averaged 20 trucks per day. Thus, the level of
traffic moving supplies over just the one route
compares with an estimated total of 28 trucks per
day entering Laos during the 1966 dry season and 17
trucks per day in the 1965 dry season (omitting
trucks said to be carrying troops in those years).
The observed size of trucks has increased each year,
and the trucks are estimated to be carrying 4 tons
per truck this dry season compared with 3 tons in
the past dry season and 2 tons in the previous dry
season.
Truck traffic into the Laotian Panhandle
began this dry season in early October compared
with mid-November last dry season and in late De-
cember in the 1965 previous season. If the current
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Table 1
Truck Traffic Observed Moving Toward Laos Through
the Mu Gia Pass Area---a7-
October 1966-February 1'967
Month
Actual
Number
Observed
Number of
Days of
Observation
Ave
Num
Truck
rage b/
ber of-
s per Day
October 1966
290
22
November 1966
532
27
December 1966 c/
12
5
January 1967
632
23
27
1-21 February 1967
718
18
40
(Tet period: 7-10
February 1967)
(385)
(4)
(96)
Total including Tet 2,184
95
23
Total excluding Tet 1,799
91
20
a. Based on reports of ground observers who usually watched
the roads during hours of darkness.
b. The actual numbers of trucks observed divided by the number of
days of observation.
c. Team withdrawn on 6 December in anticipation of bombing
of area and returned on 3 January 1967.
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level of truck traffic is maintained throughout this
dry season, traffic through the Mu Gia Pass alone
could deliver into Laos more tonnage than is esti-
mated to have been delivered by trucks over this
route during the past dry season.
Average Number of Tons Esti-
Number of Days in per mated
Season Trucks per Day Season Truck Tonnage
1965
Dry Season 19 180 2 4000
1966
Dry Season 28 210 3 17,000
1967
Dry Season 20 255 4 20,000
'Most of the supplies moving into Laos are
for consumption by the Communist forces there or,
are put into stockpiles: Probably about 20 percent
of the supplies moved into Laos are lost in, transit
or to air attack. During 1965 at least 900, tons and
during 1966 more than 7,000 tons of supplies were
moved through Laos to the border of South Vietnam.
During the current dry season only a low
level of traffic has been reported by ground ob-
servers on roads leading from the Mu Gia Pass area,
suggesting that for the most part supplies are be-
ing stockpiled near Mu Gia Pass for forward move-
ment later in the season.
Truck traffic moving south from Mu Gia Pass
can continue to move south over bypass roads to
Route 23 and further south over Routes 23 and 911.
A road-watch team located on Route 23 about
3 miles southwest of its junction with Route 12 re-
ported that from October through mid-November it saw
only 11 trucks go south. Other teams south of this
location saw no trucks until 15-19 January when.a
team located about 37 miles north of Route 9 re-
ported that an average of 45 trucks a day moved
south, past it. Since that time a daily average of
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LAOS PANHANDLE - THE LOGISTIC FUNNEL
Route
Package 2
Mukdahan
Savannhet Ban Pho
TH4(fLAND
MU G1A PASS
AREA
Ban Xam
Kang
NORTH
-VIETNAM
Batt Lang
Khang
Road
Bypass road
Se gang N'S1
Figure F-1. The Laos Panhandle: "The Logistic Funnel"
AREA
OF
MAIN
MAP
GULF OF TONKINe
Route
? i~Packag 1
Bouang
Nam
Road
- Road under construction
-- Track or trail
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about 10 trucks a day has been reported moving south
past teams on Route 23. During the 1965-1966 dry
seasons an average of about 5 trucks a day went south
past a road-watch team on Route 23.
A team on Route 911 about 3 miles south of
Route 23 reported that practically no truck traffic
moved past it from the start of the dry season until
31 December when an average of about one a day moved
south. Traffic continued at about this level until
19-21 February when about 28 trucks a day moved south.
Coverage along Route 9 and routes south of
Route 9 has been incomplete during the present dry
season, but available reports from ground observers
indicate that practically no trucks have passed
teams along the roads from which reports have been
received. It is possible, however, that trucks are
moving over routes not covered by road-watch teams.
The Movement of Supplies in Route Packages
1 and 2 ee Map)
The major logistic effort in support of the
infiltration of supplies into South Vietnam is con-
centrated in the areas covered by armed reconnais-
sance Route Packages 1 and 2, corresponding to that
part of North Vietnam south of Vinh. The bombing
campaign has not adversely affected North Vietnam's
ability to move supplies south of Vinh, despite the
heavy weight of the total air effort in this region.
Pilot sightings of watercraft along the
coast and in the inland waterways of North Vietnam
have been heaviest in the area of Vinh between 180
and 190 N. The key transshipment areas at Vinh,
Quang Khe, and Dong Hoi are operational and con-
tinue to perform a key function in the movement of
supplies south. Truck traffic, used for distrib-
uting material to the DMZ or into Laos, continues
to flow through the Mu Gia Pass. According to road
watch reports from the Mu Gia area, an average of
80 tons a day have been trucked along this route
into Laos since October. Truck sightings also con-
tinue to be heavy along Route 1A south of Dong Hoi,
and on Routes 101 and 102, near the DMZ. The road
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network, while cratered innumerable times, has been
kept repaired so that traffic continues to move. The
construction of new routes, bypasses, bypass bridges
and ferries has further decreased the effectiveness
of the bombing.
The light-weight rail line south of Vinh con-
tinues to be used in certain sections, although bomb-
ing has limited its use. The North Vietnamese are
currently rebuilding the inoperable section in the
southern part of Route Package 1 and extending it
towards the DMZ. Also, repair work was noted on the
spur from Tan Ap towards the Mu Gia Pass before and
during TET. These two improvements in the rail line
will greatly increase the logistic capability of the
North Vietnamese in the area south of Vinh.
We estimate that the total amount of sup-
plies moved into southern North Vietnam during 1966
has been at least at the levels estimated for De-
cember 1965. In that month it was estimated that
20,000 tons of supplies (rice, POL, and military
goods), were transported into the four southern
provinces of NVN. The portion of this moved south
from Vinh is not known, but COMINT intercepts indi-
cated that at least 7,000 tons were moved to the
Tan Ap area near Mu Gia Pass during that month.
Bombing of the roads and rail line in the southern
area has resulted in the Vietnamese shifting a con-
siderable amount of traffic to water transport, but
on the whole it appears that supplies have continued
to move south at least at the December 1965 rate if
not higher. The bombing has made the movement diffi-
cult and costly, but the North Vietnamese have been
adept at maintaining a transport system adequate to
provide-whatever supplies they decide are needed in
the south.
Effect of the Bombing on Infiltration of Men
and Supplies
General Appraisal
Despite the increased efforts to interdict
the flow of men and supplies from North Vietnam to
South Vietnam during 1966, North Vietnam was able
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to increase its support of the insurgency in South
Vietnam. The air campaigns against targets in Laos
and North Vietnam were not able to prevent about a
threefold increase in the level of personnel infil-
tration in 1966. The external logistic support needed
to maintain the expanded Viet Cong/North Vietnamese
force in South Vietnam has been adequate. The flow
of supplies through Laos to the border of South Viet-
nam in 1966 was almost eight times the level of 1965.
Data on current supply movements indicate that they
will be at least at1965,levels and may be consider-
ably higher.
Despite the intensified bombings the North
Vietnamese have been able to improve existing supply
networks and to complete significant amounts of new
road construction. The road network through Laos,
for example, was expanded from about 150 miles at
the start of the bombings to 650 miles at the end
of 1966. An elaborate system of bypass roads and
new construction was also undertaken in the southern
parts of North Vietnam. As a result of these pro-
grams the North Vietnamese currently have an infil-
tration network of higher capacity, greater diversity,
and less vulnerability to air attack than they had
when the bombings started.
These developments have not been without
high costs. The diversion of from 600,000-700,000
full-time workers to respond to the air strikes has
reduced North Vietnam's mobilization potential.
Moreover, the burden of infiltrating men and sup-
plies has been made more costly and taxed the capa-
bilities and resources of the country.
Magnitude of the Bombing Program
The weight of air attack against target sys-
tems in North Vietnam and in Laos has accounted for
an increasing share of the total air effort in sup-
port of US objectives in the Vietnam war. During
1966 the number of sorties flown against targets in
North Vietnam was nearly 2.7 times the number flown
in 1965; sorties flown against targets in Laos were
about 4.8 times the number flown in 1965. The size
of this effort and its relation to total air operations
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in Southeast Asia are shown in the following tabu-
lation:
1965
1966
Number
of
Perce
of
Number Percent
of of
Operation
Sorties
Total
Sorties
Total
North Vietnam
55,210
30
147,850
35
Laos
16,030
9
76,110
18
North Vietnam and
Laos Combined
71,240
39
223,960
53
South Vietnam
110,310
61
204,120
47
Total South-
east Asia
181,550
100
428,080
100
As the air effort directed against targets in
North Vietnam has grown, it has become in effect a
massive interdiction program. During 1966, for ex-
ample,?over 98 percent--145,000--of all sorties flown
over North Vietnam, and the greater part of the
sorties flown in Laos--76,000--were allocated to the
interdiction program. About 70 percent of the com-
bined effort was concentrated in the so-called logis-
tic funnel--Routes Packages 1 and 2 in North Vietnam
and the Laotian Panhandle.
Direct Effects of the Interdiction Campaign
Aerial photography, pilot reports, and other
intelligence sources indicate that the interdiction
campaign has imposed high costs on North Vietnam, in
both material and human losses. Some of the major
losses attributable to the interdiction campaign in
both Laos and North Vietnam include:
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Bridges Destroyed or
Damaged* 492
Transport Equipment De-
stroyed or Damaged
Vessels 12,900
Vehicles 7,925
Railroad Stock 3,367
Casualties from Armed
Reconnaissance 28,000-
30,000
The cost of the damage to transport facili-
ties and equipment alone ranges from $65-70 million.
In addition to the loss of manpower represented by
casualties resulting from the interdiction program,
North Vietnam has had to commit large amounts of
labor to maintain distribution and logistic activi-
ties. About 125,000 workers are committed on a
full-time basis to road and rail construction, main-
tenance and repair activities. At least 50,000 full-
time workers have had to be added to the transport
labor force and about 45,000 full-time workers are
committed to dispersal and other emergency programs
forced by the interdiction program. Finally, as
many as 100,000-200,000 workers are required to sup-
port these activities on a part-time basis.
Maintenance of the Infiltration Network
General
Throughout the bombings the North Viet-
namese have mounted an intense effort to keep LOC's
and infiltration networks open. They have con-
stantly increased their ability to counter the ef-
fects of US/GVN air strikes and, indeed, have in-
creased the capacity of the transport network. The
roads in North Vietnam, primarily, south of Hanoi,
have been kept open almost continuously since the
*As confirmed by aerial photography.
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start of the bombing by the extensive use of-bypasses to
destroyed highway bridges and the construction of
new alternative routes. The following tabulation
shows the extent of these improvements during 1965
and 1966 in North Vietnam.
Miles
Type of Construction
Road
Railroad
Newly developed routes
650
30
Improvements to existing routes
350
90
Short bypasses to existing routes
150
60
A similar effort in Laos during the same
period resulted in the expansion of the infiltration
network in Laos from 150 miles to a total of 650 miles.
The improvement and maintenance of the in-
filtration network has continued in 1967, reflecting
North Vietnam's determination to maintain an effective
and viable system for moving men and supplies into
South Vietnam.
New Construction Activity During 1967
North Vietnam
North Vietnamese workers continued to
improve existing highway routes and construct alternate
routes during the first two months of 1967. Completion
of the 68-mile section between Ha Tinh and Quang Khe of
the inland alternate to Route 1A was slowed however by
a combination of air strikes and flooding caused by
heavy rains. Although sections of the new route are
serviceable, workcamps in MR IV during January were
ordered to concentrate on repairs to existing routes.
Intensified efforts to repair bridges and ferries were
made in MR IV during January and early February in
preparation for the increased traffic scheduled to move
during the Tet' bombing standdown.. Route 15 to Mu. Gia
Pass and Route IA south of Dong Hoi were improved to
handle the heavy holiday traffic.
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Repairs to railroad bridges in North
Vietnam and the construction of multiple bypass bridges
at strategic crossings continued at approximately the
same pace in 1967. The rail lines from China and the
port of Haiphong were kept open almost continually
while the line south from Hanoi was open periodically
to Thanh Hoa and sporadically as far as Vinh. The 30-
mile standard gauge rail line from Kep west to Thai
Nguyen, was open in early December. The conversion to
dual gauge (meter and standard gauge) of the rail line
between Kep and the China border was probably complete
by late 1966, and there is evidence of preparations to
convert the Thai Nguyen-Nguyen Khe rail line and the
Kep-Hanoi line to dual gauge.
Road maintenance and repair in the Laos
Panhandle continued during early 1967 together with
small amounts of new construction of bypass roads. The
entire road system which was rapidly expanded during
the 1966 dry season was reopened to through traffic via
Routes 92 and 96 by the first week of January. Roads
through Mu Gia Pass have continued to be serviceable
.and Route 23 is now being used along with 911 to the
Tchepone area. Although the alternate border crossing
from North Vietnam via Route 912 was kept open during
the past rainy season, it appears that Mu Gia Pass is
also being used again. Route 922 through the Se La Mang
River Valley is being extended across the Laos/South
Vietnam border into the Ashau Valley in Quang Tri Prov-
ince. This is the first time that a motorable road
from the Ho Chi Minh Trail has been noted extending into
South Vietnam. Visual reconnaissance from mid-February
indicated that Route 922 was under construction across
the border and that trucks are now using it to within
0.5 miles of the border. A new road is under construc-
tion east of Route 9. When completed, it will provide
a bypass between Route 23 via Muong Phine and Route 92
near Muong Nong. South of Attopeu, Route 110 underwent
considerable improvement during January and February
and at least 3 short bypasses were constructed around
chokepoints. Route 97 which provides the road connec-
tion between Route 110 and Siem Pang, Cambodia was re-
opened to traffic in early January.
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Countermeasures and Speed of Response
The work units in North Vietnam and Laos
have developed a high degree of skill during the past
two years of bombing in making repairs and in con-
structing bypasses to damaged LOC's. Speed and sim-
plicity of repair has been the hallmark of their pro-
gram. Hand tools and local building materials such
as timber, stone, and gravel are the principal means
of repairs. Destroyed bridges are frequently replaced
by fords, ferries, culverts, and bypass bridges. In
some cases, as many as four alternate crossings have
been constructed to bypass a single bridge. The North
Vietnamese have developed a new bridging technique
using steel cables and removable bridge decking as a
relatively rapid means of bridge replacement and to
reduce the vulnerability of bridges to air attack.
Most of the work is undertaken at night to protect
workers from attack. In addition, the North Vietnam-
ese have relied heavily on waterborne traffic to move
goods around damaged areas still under repair. Boats,
barges and rafts constructed on the site have been noted
in photography. Transshipment activities have been
widely dispersed and concentrations of shipping have
been avoided.
The North Vietnamese now have highly or-
ganized repair crews and have built multiple bypasses
so that the continued movement of essential materials
is insured. The North Vietnamese have carried out
their successful countermeasures through a tightly
controlled system of work camps and in the northern
part of North Vietnam they are further aided by Chi-
nese engineer troops. The labor force on LOC's in
North Vietnam and in the Laos Panhandle has doubled
since July 1965. Substantial inputs of Chinese Commu-
nist Engineering troops working primarily on North
Vietnamese rail and road connections with China have
also helped to ensure the continued operation of vital
supply lines and freed North Vietnamese labor for de-
ployment elsewhere in the country. It is estimated
that up to 125,000 workers and Chinese engineering
troops are currently engaged in the full time repair
of LOC's in North Vietnam and in the Laos Panhandle.
To supplement this full-time labor force, at least
100,000 and probably as many as 200,000 day laborers
perform some road and bridge repair in addition to
their principal duty in agriculture.
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Prospects for Interdiction
About 70 percent of all air strikes in
North Vietnam and Laos during 1966 were carried out
against targets in the "logistic funnel" which com-
prises Route Packages 1 and 2 in North Vietnam and
the road network through the Laotian Panhandle. More
than 250 bridges in the"logistic funnel"were con-
firmed by aerial photography to be damaged or de-
stroyed. Despite this intensive bombing, the supply
lines from North Vietnam to the VC/NVA forces fight-
ing in the south have been kept open.
Even if the total air attack were con-
centrated on the "logistic funnel," we estimate that
North Vietnam could maintain the flow of men and
supplies. The North Vietnamese could respond ade-
quately to the intensified bombing by increasing the
size of the labor force engaged in repair work by
about 30 percent. This labor would be drawn from
areas no longer being bombed. Moreover, the North
Vietnamese could strengthen their air defenses in
the "funnel" area to counteract the new bombing pro-
gram. For example, a SAM site was established within
target range of Mu Gia Pass within 2 weeks after the
first bombing raid by B-52's in April 1966.
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Top Secret
Top Secret
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