NVA INFILTRATION AND UNIT DEPLOYMENTS SINCE SEPTEMBER 1971

• Document Type: SPECIALCOLLECTION
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• Document Number (FOIA) /ESDN (CREST): 02897838
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• Document Creation Date: March 16, 2022
• Document Release Date: May 13, 2016
• Case Number: F-2016-00757
• Publication Date: November 1, 1972

CIA OE1. 1M 72-159
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DIRECTORATE OF
INTELLIGENCE
Intelligence Memorandum
NVA Infiltration and Unit Deployments Since September 1971
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ER IM 72-159
November 1972
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CENTRAL INTELLIGENCE AGENCY
Directorate of Intelligence
November 1972
INTELLIGENCE MEMORANDUM
NVA INFILTRATION AND UNIT DEPLOYMENTS
SINCE SEPTEMBER 1971
Summary and Conclusions
I. Hanoi's decision to abandon the protracted warfare strategy
employed for the past several years in favor of large-unit conventional
warfare in 1972 has resulted in an unprecedented manpower commitment
to the southern war zones during the past year. From September 1971
through August 1972, Hanoi sent out of North Vietnam some 248,000
personnel � 191,000 during the past dry season (September 1971 through
June 1972) and 57,P00 during the wet season (July-August 1972). Of the
total commitment, about 187,000 were sent to Military Regions (MRs) 1
and 2 in northern South Vietnam; 38,000 to southern Cambodia and MRs 3
and 4 in South Vietnam; and 23,000 to southern Laos and/or northeast
Cambodia. Approximately 179,000 (or 72%) of the 248,000 infiltrated
south via the regular infiltration pipeline through Laos, while an additional
69,000 deployed into northern MR 1 in regular military units directly across
the DMZ. A summary of Hanoi's out-of-country manpower investment, by
destination, is shown in Table 1 and Figure 1.
2. The North Vietnamese manpower commitment to the war zone
since September 1971 even ?.xceeds that sent south between September
1967 and August 1968. In the 1967/68 period, about 230,000 troops(1) �
50,000 men in organic NVA units and 180,000 other infiltrators � moved
into the war zone. In terms of organic units, this year's deployment of
Note: This memorandum was prepared by the Office of Economic Research
and coordinated within CIA.
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Table 1
Hanoi's Manpower Commitment to the Southern War Zones
Destination
Regular
Infiltration Cycle Wet Season
(Sep 1971 -Jun 1972) (Jul-Aug 1972) Total
GVN MRs 1 and 2
82,000
36,000
118,000
VC MR TTH
35,000
35,000
70,000
VC MR 5
17,000
0
17,000
VC B-3 Front
30,000
1,000
31,000
GVN MRs 3 and 4/Cambodia
38,000
0
38,000
Southern Laos/northeast Cambodia
16,000
7,000
23.000
Subtotal
136 000
43,000
179 000
Unit deployment outside the
infiltration systema
55 000
14,000
69,000
Total
191,000
57,000
248,000
a. All organic unit deployments outside regular infiltration channels went to VC Military Region
Tri-Thien-Hue (TTH).
89,000 men (69,000 outside normal infiltration channels and about 20,000
in ordinary infiltration groups) also is by far the largest ever sent south.
The total manpower investment since September 1971 increased the
VC/NVA force structure in Laos, Cambodia, and South Vietnam to more
than 350,000 men in August 1972. This is the largest VC/NVA force
structure outside North Vietnam thus far during the war.
3. This unparalleled flow of manpower to the southern war zones
was made necessary by Hanoi's shift to a conventional warfare strategy
for the 1972 campaign. The decision to change strategies clearly was taken
before the beginning of the 1971/72 cycle � in order to provide the time
to train and equip the large numbers of personnel to be sent south. Early
in the dry season infiltration cycle, Hanoi began sending large numbers of
personnel, including one full infantry division and elements to form two
others, into the western highlands of South Vietnam's MR 2 and into
Cambodian areas adjacent to MRs 3 and 4. As these forces were being
positioned and supplied, Hanoi also deployed an invasion force of four
infantry divisions along with armor and artillery units into the DMZ/Quang
Tri Province area of northern South Vietnam. In late March the Communists
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began their offensive by attacking South Vietnamese units just south of
the DMZ, and this soon was followed by thrusts from the newly positioned
forces into the western highlands of MR 2 and the An Loc area of MR 3.
4. As the battle wore on, South Vietnamese resistance stiffened and
the Communists abandoned, at least temporarily, their attempts to overrun
Kontum and An Loc cities and concentrated their efforts against government
positions in Quang Tri and Hue. By June they had ceased sending additional
manpower to their forces in MRs 2, 3, and 4. Their unprecedented troop
commitment to the Quang Tr-Hue area in northern MR 1, however,
continued with the deployment from North Vietnam of two fresh infantry
divisions and with the highest level of wet season (July-August 1972)
infiltration ever recorded in this area.
Discussion
The 1971/72 Dry Season Infiltration Cycle(2)
5. During the period September 1971 through June 1972, Hanoi
inserted about 136,000 men into the regular infiltration pipeline destined
for the southern war zones � South Vietnam, Cambodia, and southern
Laos.(3) This surpasses infiltration during the 1970/71 cycle, when about
106,000 men were sent south, and is more than double the 1969/70 level,
when only about 66,000 men were dispatched from North Vietnam. The
higher level of infiltration experienced during the 1971/72 season resulted
both from the desire of the North Vietnamese to reinforce their combat
and support structure in the south and the requirement to preposition
replacements for losses expected from the large:scale offensive planned for
South Vietnam in the spring of 1972.
2. During the 1971/72 dry season, changes in North Vietnamese infiltration and
communications practices reduced our ability to monitor certain aspects of personnel
infiltration. For example, the practice of sending large numbers of personnel directly
across the DMZ into northern South Vietnam caused them to bypass the Binh Trams
in Laos which are important sources of much of our infiltration data. (The current
infiltration routes are shown in Figure 2.) As a result, the estimate of enemy personnel
moving into northern South Vietnam, especially VC MR Tri-Then-Hue (TTH),is more
tenuous than that for the other areas in South Vietnam.
3. As used in this memorandum, regular infiltration denotes groups,usually of about
500 NVA troops that move south through the infiltration system, which have been
assigned infiltration group designators by the North Vietnamese logistical administrators
for purposes of control and accounting
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6. A heavy input of personnel into the infiltration system began
in October, one month later than during the 1970/71 infiltration cycle.
In four months, October through January, an average of about 20,000 men
a month entered the infiltration pipeline, compared to an average of about
15,000 a month for a similar period in the 1970/71 cycle. Infiltration also
continued at a high rate through the later months of the infiltration cycle --
in support of the large-scale NVA offensive in South Vietnam which had
begun at the end of March 1972.
7. Of the 136,000 NVA infiltrators entering the pipeline to the
south, about 120,000 were destined for South Vietnam and Cambodia, while
the balance infiltrated into southern Laos Of northeastern Cambodia. An
estimated 5% of the total number of infilt:ators (approximately 6,800)
either fell victim on the trail to accident, sickness, or Allied attacks or
returned to North Vietnam as deserters or training cadre after supervising
the delivery of individual groups.
8. In addition to the 136,000 men sent south via the infiltration
system, another 55,000 troops entered the war zone in organic units
apparently outside regular infiltration channels. This compaies to an organic
unit deployment of about 24,000 during the 1970/71 dry season. The units
moved into South Vietnam's MR 1 either din ctly across or just around
the western end of the DMZ. This organic unit deployment, coupled with
regular infiltration, brings Hanoi's commitment to the war zone during the
1971/72 dry season infiltration cycle to approximately 191,000 men and
is the largest since the 1967/68 season. The organic units which have
deployed out of North Vietnam to the south during the past year are shown
in Table 2.
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Table 2
Organic Units That Deployed
from North Vietnam to the War Zone
During the Period September 1971
Through August 1972
Military Region I
304th Infantry Division
9th Infantry Regiment
24th Infantry Regiment
66th Infantry Regiment
68th Artillery Regiment
308th Infantry Division
36th Infantry Regiment
88th Infantry Regiment
102nd Infantry Regiment
312th Infantry Division
141st Infantry Regiment
165th Infantry Regiment
209th Infantry Regiment
320B Training Division
48B Infantry Regiment
64B Infantry Regiment
Military Region 2
320th Infantry Division
48th Infantry Regiment
52nd Infantry Regiment
64th Infantry Regiment
Two battalions of the former
54th Artillery Regiment
Two battalions of the 203rd
Arntsr Regiment
324B Infantry Division
29th Infantry Regiment
803rd Infantry Regiment
812th Infantry Regiment
325th Infantry Division
18th Infantry Regiment
95th Infantry Regiment
101st Infantry Regiment
270th Regiment/711th Infantry
Division
202nd Armor Regiment
203rd Armor Regiment
38th Independent Artil-
lery Regiment
45th Independent Artil-
lery Regiment
58th Independent Artil-
lery Regiment
84th Independent Artil-
lery Regiment
164th Independent Artil-
lery Regiment
166th Independent Artil-
lery Regiment
Military Region 3
271st Infantry Regiment
18th Infantry Regimenta b
Three battalions of the 203rd
Armor Regiment
Military Region 4
Z-17 Infantry Regiment (deployed
as the 95th Regiment)b
Z-18 Infantry Regiment (deployed
as the 101st Regiment)b
a. Appears to have been broken down and used as fillers for VC/NVA units in MR 3.
b. Generated and trained in North Vietnam by the 325th Division sometime prior
to the current offensive.
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GVN MRs 1 and 2
11. From September 1971 through June 1972, Hanoi sent at least
137,000 men into South Vietnam's two northern military regions.(4) Of
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4. For the distribution of manpower committed by South Vietnam and Communist
administrative divisions, see Figure 3. There is substantial evidence that the movement
of organic units outside regular infiltration channels occurred only into northern MR 1 --
unlike the personnel flow to the remainder of South Vietnam. A review of the avaqable
captured documents and prisoner/rallier interrogation reports from the organic units
which moved into northern MR 1 during the 1971/72 dry season has failed to turn
up any references to infiltration group designators. This is in sharp contrast to the
information obtained from such sources on units which moved into MR 2 and areas
farther south which did specify infiltration group designators. It seems likely that if
the units now in northern MR I had moved through infiltration channels there would
have been some references to their infiltration group designators.
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this total, about 82,000 men moved down in regular infiltration groups
and another 55,000 or so deployed into northern MR 1 in organic units
outside regular infiltration channels. This manpower commitment is a 240%
increase over that of the 1970/71 infiltration season, when only 40,000
men (35,000 infiltrators and 5,000 in units) were sent into these two
military regions.
12. The total North Vietnamese manpower commitment to northern
MR 1 (VC MR Ti'!-!) during this past infiltration cycle was about 90,000
men (35,000 in infiltration groups and 55,000 men in organic units). This
commitment was more than eight times that which occurred during the
1970/71 season, when only 11,000 men (6,000 in infiltration groups and
5,000 in organic units) moved into the area. The additional units which
moved into northern MR 1 increased the number of Main Force combat
units there to a level above that of Tet (February) 1968.
13. The movement of organic units into northern MR 1 and into
MR 2 began in February 1972 with the deployment of the 324B NVA
Division into Thua Thien Province. The division then began offensive
operations against the 1st ARVN Division's complex of firebases west of
Hue. Also, the 320th NVA Division infiltrated from North Vietnam to the
western highlands of MR 2. It began offensive operations in March against
major elements of the 22nd ARVN Division and airborne divisions
northwest of Kontum city, driving the South Vietnamese units back into
the town.
14. During March the 304th NVA Division deployed from Quang Binh
Province in southern North Vietnam to western Quang Tri Province,
initiating the Communist Easter Offensive by attacking the 3rd ARVN
Division's firebases in the vicinity of Cam Lo. The largest influx of organic
units to MR 1 thus far during the entire war occurred during April. These
units included the 308th NVA Division, major elements of the 325th and
320B NVA Divisions, two armor regiments, and four artillery regiments.
These forces launched successful attacks against South Vietnamese units
in the vicinity of Dong Ha and Quang Tri cities. In addition, a second
generation of the 270th NVA Independent Regiment infiltrated into Quang
Nam Province during April and was subordinated to the 711th NVA
Division. This division has been conducting offensive operations in the
Quang Nam/Quang Tin Province border area near the Que Son district
capital.
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16. Personnel infiltration to VC MR 5 (the central coastal portion
of GVN MRs 1 and 2) was about 17,000 men during the 1971/72
infiltration cycle � all in regular infiltration groups. This compares to about
14,500 men sent to the area during the 1970/71 season. Men included in
this infiltration provided replacements for the NVA 3rd Division, which
occupied the three northern districts of Binh Dinh Province early in the
Communist offensive. (South Vietnamese forces recaptured the district
capitals in northern Binh Dinh in August.)
17. Hanoi's manpower strategy in GVN MRs 1 and 2 was developed
to replace losses incurred by units which had particpated in blocking
operation Lam Son 719 in Laos and had retuned to South Vietnam and
to augment its forces in preparation for the 1972 Easter Offensive. Between
December 1971 and March 1972, a substantial number of infiltrators were
sent to the northern provinces to provide replacements for units of the
B-5 Front and MR TTH. These units had suffered heavy losses in the summer
and fall of 1971. Replacements also were sent to units of the B-3 Front
in the western highlands during this period. Then the four divisions deployed
into South Vietnam in March and April provided the forces to carry out
the attacks during the recent offensive � which have been among the
heaviest of the war. Replacement infiltration has continued at high levels
throughout the offensive to maintain the strength of enemy units in combat.
The COSVN Area
18. Approximately 38,000 men traveled to the COSVN area
(Cambodia and South Vietnam's MRs 3 and 4) during the 1971/72
infiltration cycle. Included in this total were about 10,000 men who moved
down in organic units with regular infiltration group designators. As a result
of these unit deployments, the .COSVN forces in MR 3 were augmented
by at Last two and possibly three regiments from North Vietnam, while
enemy forces in MR 4 were reinforced by at least two new NVA infantry
regiments.
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20. The organic units which moved to the COSVN area this past
season began their journeys early in the infiltration cycle. Both the 271st
Independent Regiment and three regiments of a divisional entity (apparently
generated and trained by the 325th NVA Division) departed from North
Vietnam in late 1971. They arrived in the COSVN area in Cambodia in
late February and were moving into South Vietnam by mid-April. The 271st
Independent Regiment was attached to the newly formed C-30B Division,
which then moved into Hau Nghia and southern Tay Ninh Provinces of
MR 3. One regiment of the divisional entity apparently generated by the
NVA 325th Division infiltrated into MR 3 and appears to have been broken
down and used to fill out understrength VC/NVA units in the region. The
other two regiments moved into the Parrot's Beak area of Cambodia and
were redesignated the Z-17 and 2-18 Regiments in GVN MR 4. In addition,
three battalions of the 203rd Armor Regiment deployed into southern
South Vietnam during the spring of 1972, the last unit arriving in Binh
Long Province of MR 3 in May.
21. The Communist manpower strategy for the COSVN area this past
dry season was to use early infiltration arrivals to strengthen enemy units
in Cambodia prior to their deployment into MR 3 and MR 4, and then
to use later infiltration arrivals as replacements for losses as the offensive
progressed. About 27,000 men deployed from Cambodia into MR 3 for
the offensive, and as many as 10,000 of them were newly infiltrated
personnel. About 11,000 men from the Phuoc Long Front (also known
as the 1st NVA Division) and two newly infiltrated regiments deployed
from Cambodia to GVN MR 4 for the offensive as well. The Phuoc Long
Front elements were driven back into Cambodia soon after their initial
penetration, although they have since returned. Additional infiltrators were
also used to fill out understrength units in both MR 3 and MR 4 just
prior to the offensive. Several units in both these regions were substantially
understrength before these infiltrators arrived. (The geographic pattern of
infiltration to South Vietnam during the period September 1971 through
June 1972 is shown in Figure 3.)
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Southern Laos/Northeast Cambodia
22. Most of the 16,000 personnel destined for southern Laos and
northeast Cambodia(5) during the 1971/72 infiltration cycle probably were
used to expand the logistic structure. Since the end of the 1970/71 dry
season, the North Vietnamese have expanded their logistical apparatus in
the Laotian Panhandle and northeast Cambodia by forming three new
transportation groups and seven new subordinate Binh Trams. North
Vietnam also sent a number of replacement personnel to combat units in
southern Laos, besides deploying in mid-1972 two infantry battalions which
formed the nucleus of the new 19th Regiment. This regiment appears to
be subordinate to the 968th Infantry Division, created in January 1972
from units formerly subordinate to Front Y -- the NVA tactical authority
for the southern part of the Panhandle.
Northern Laos
23. Although the aggregate annual infiltration flow to northern Laos
cannot be estimated with the degree of reliability of that for the rest of
Indochina, more than 7,000 personnel were detected deploying in units
and fine' groups to the Plaine des Jarres area during the 1971/72 dry season.
Some 90% of the detected flow occurred during the six-week period between
15 October and 30 November 1971. This infiltration included the
141st Infantry Regiment and support elements of the 312th Division, the
335th Infantry Regiment, the 21F,th Antiaircraft Artillery Regiment, and
elements of the 351st Artillery Command. The remaining 10% were
detected deploying during February 1972 and undoubtedly were used as
replacements to offset some of the personnel losses suffered by NVA units
during the dry season fighting and for logistics-related activities such as
the road building effort.
The Rainy Season
24. During the height of the rainy season � July and August � Hanoi
sent south some 57,000 personnel � 50,000 to South Vietnam and about
7,000 to southern Laos and northeast Cambodia. This manpower flow
represents the highest level of personnel infiltration ever during a rainy
season. Of the 50,000 sent to South Vietnam, 36,000 came down in regular
infiltration groups and about 14,000 entered in organic units(6) directly
5. Some of the personnel destined for the logistic structure in southern Laos may
have moved into northern South Vietnam when major logistic elements relocated there
from southern Laos to support the offensive.
6. These units include the ?5th and 101st Regiments of the 325th NVA Division,
the 165th Regiment of the 312th Division, and the 45th Artillery Regiment of the
B-5 Front.
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across the DMZ outside infiltration channels. Almost all of this infiltration
appears to be a direct result of the need for additional replacements during
the current offensive in northern MR 1 .
25. Only 1,000 of the 50,000 men who infiltrated into South Vietnam
during July and August moved farther south than GVN MR 1. These
personnel were destined for the western highlands of the B-3 Front, where
heavy personnel losses in May-June depleted enemy units. No rainy season
infiltration was detected moving to the COSVN area. One reason for this
lack of infiltration activity to the southern region of South Vietnam is
the difficulty of moving personnel long distances through the Laotian
Panhandle during the wet season. It also is likely that available replacements
currently have a lower priority for COSVN than for MR I. By contrast,
the Communists did dispatch a significant number of infiltrators � more
than 15,000 � to the COSVN area during July and August of 1968 to
replace losses incurred during the 1968 Tet and May offensives.
26. The 57,000 personnel committed to the war zone during July
and August increases Hanoi's total manpower commitment to the south
since September 1971 to about 248,000 men. This commitment has now
surpassed the level attained in 1967/68, when about 230,000 men in
infiltration group.; and organic units were sent south in support of the 1968
General Offensive.(7) Furthermore, in 1968 several of the line divisions
Table 3
North Vietnarr.,...�:e Manpower Deployment
to Southern Laos, Cambodia, and South Vietnama
1967/68
1968/69
1969/70
1970171
1971/72
Dry season
(Sep-Jun)
200,000
105,000
76,000
130,000
191,000
Wet season
(Jul-Aug)
30,000
1,000
9,000
Negl.
57,000
Total
230,000
106,000
85,000
130,000
248,000
a. Rounded to the nearest thousand. Manpower deployment includes both unit
deployments and replacement and specialist infiltration.
7. For an illustration of NVA manpower commitment over time, see Table 3.
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which had deployed into South Vietnam began trr.)ving back to North
Vietnam by mid-year. By the end of October, al of these divisions had
returned to the north. ThN year, none of the orguic units which infiltrated
have yet returned north, and there are no present indications that they
plan to do so.
Outlook for the 1972/73 Infiltration Cycle
27. Until a ceasefire takes effect, it is likely that the high levels of
infiltration observed over the past year will continue into the southern war
zones. During the first two months of this dry season's infiltration cycle
(September and October) some 1 6,000 personnel have entered the
infiltration pipeline, about double the number entering during the same
period a year ago. High levels of infiltration have continued into northern
South Vietnam and substantial numbers of personnel have recently been
detected moving to the CCSVN area as well. The resumption of infiltration
to COSVN coupled with tile continuing infiltration to the north indicates
that the Communists are replacing the heavy losses incurred by their forces
during the offensive since 30 March. If additional major offensive activity
is planned by the Communists, continued high levels of personnel infiltration
during the next few months will almost certainly be required.
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