NORTH VIETNAMESE CAPABILITIES TO COUNTER A US COURSE OF ACTION

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78T02095R000600360001-4
• Release Decision: RIFPUB
• Original Classification: S
• Document Page Count: 11
• Document Creation Date: December 20, 2016
• Document Release Date: March 29, 2006
• Sequence Number: 1
• Publication Date: October 1, 1969
• Content Type: IM

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North Vietnamese Capabilities to
Counter a US Course-of Action
October 1969
Oct 1969 Typescript IM, North Vietnamese Capabilities to Counter
a US Course of Action, October 1969
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SECRET
SENSITIVE
DIRECTORATE OF
INTELLIGENCE
Intelligence Memorandum
NORTH VIETNAMESE CAPABILITIES TO COUNTER A US COURSE
OF ACTION
SECRET
SENSITIVE
OCTOBER 1969
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CENTRAL INTELLIGENCE AGENCY
Directorate of Intelligence
6 October 1969
North Vietnamese Capability
to Counter a US Course of Action
Introduction
This memorandum is responsive to a request for
an analysis of the capabilities of the North Viet-
namese to counter a US mining program by adopting
countermeasures that insure continued access to
North Vietnam by oceangoing and coastal shipping.
The following assumptions are used in the analysis:
1. A US mining program has suc-
cessfully denied access to North
Vietnam's major and minor ports, and
all feasible lightering areas, by
both oceangoing and coastal shipping.
2. Both Communist China and the
Soviet Union are committed to provide
the equipment and personnel necessary
for the implementation of the North
Vietnamese countermeasures.
The focus of this memorandum is on the gross
capabilities of North Vietnam to counter mining
operations with indigenous resources or resources
provided by the USSR and Communist China. The
memorandum also considers the feasibility of more
simple countermeasures such as resort to lightering,
over-the-beach operations, and the use of shallow-
draft coastal craft. The memorandum does not
attempt to analyze the specific techniques and
methods that might be used to sweep minefields.
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The Mining Program
1. A successful mining of the water approaches
to North Vietnam's major and minor ports and its
coastal waters would require two general types of
mines those designed to attack shallow-draft
craft used for coastal shipping and on inland
waterways, and mines designed to attack larger,
oceangoing ships. At the present time, both types
are available in the US munitions inventory. The
.first, the MK-36 destructor, is a magnetic device
which has already seen use against waterborne
traffic in the Vietnam war. Strictly speaking,
this device is a land mine and has been used widely
in that role. The MK-36 is too small to be an
effective weapon against heavy steel-hulled ships,
although it is effective against smaller wooden-
hulled vessels. The second, the MK-50 mine, is an
aircraft--planted bottom mine that is activated by
the low frequency acoustic field of a ship. It is
effective in water depths up to 60 feet and is
particularly effective against ships of 60 to
1,000 tons displacement. One feature which makes
it particularly invulnerable to neutralization is
its delayed action arming device which can be set
to delay from 10 minutes to as long as 90 days.
North Vietnam has demonstrated a capability against
the MK-36 but has not yet had to cope with the
MK-50.
The MK-36 Experience
2. The US experience during the Rolling
Thunder program when the MK-36 was used against
North Vietnams waterborne traffic suggests that
the weapon was not a very effective interdiction
device. During the Rolling Thunder campaign, some
70,000 MK-36 weapons were deployed against land
and waterway targets in North Vietnam. On balance,
the MK-36's performance record seems very uneven.
The monthly seedings of MK-36 weapons reached a
high of almost 12,000 in May 1968. More MK-36
devices probably were dropped at the Quang Khe
transshipment facility than at any other single
mining target. Nevertheless, this facility demon-
strated a sustained capability to handle large
concentrations of watercraft during the periods
of most intensive mining. While the destructor
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disrupted waterborne traffic in a number of
instances and hampered the repair of damaged
bridges, photographic evidence showed that the
weapon failed to deny the NorthVietnamese the
use of any important waterway or land target for
more than a brief time. The enemy demonstrated
considerable ingenuity in countering the mine.
Employing relatively simple measures such as
floating rafts, barges, or sampans towing empty
POL drums, the enemy was able to neutralize the
mine fields, although at the price of some loss of
life, watercraft, and cargo.
3. It is unlikely that the MK-36 alone could
prevent the enemy's use of sampans and barges for
lightering operations along the coast and on
inland waterways. At best, such traffic would be
hampered by an MK-36 mining program, and the enemy accepting the heightened risks -- would be required
to invest time, effort, and some casualties to
offset its effect. It is unlikely that either the
USSR or Communist China would be required to assist
North Vietnam in anti-mining operations against the
type of threat represented by the MK-36.
CapabilitiLLe's Against' the MK-,50
4. The approaches to the port of Haiphong are
well suited for an MK-50 mining program. US navi-
gation charts indicate a 25-mile stretch of channel
which could be mined in the outer anchorage and
well into the port itself. Furthermore, selective
mining would be hydrographically feasible over a
wide area in the vicinity of the port, thus making
alternative approach routes hazardous.
5. North Vietnam's naval inventory consists of
three submarine chasers, 13 motor torpedo boats,
22 motor gunboats, and an estimated 50 service
craft. None of these craft are capable of effec-
tively sweeping bottom-influence mines such as the
MK-50. Left to its own capabilities, North Vietnam
would have only a few primitive options for coping
with the mines. Machinegun fire into the mine case
.could be employed against mines laid in relatively
shallow waters, but this method requires long
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periods of sustained fire and there is little
chance of success. Dragging operations using
trawler nets, steel barrels, and the like might be
effective against shallow-positioned mines but would
at. best destroy only a few individual mines and
would not neutralize the fields themselves. The
use of underwater search teams is also possible,
but the major ports of North Vietnam have bottom
sediments, primarily mud and sand, which would make
such measures exceedingly difficult.
6. Acoustic minesweeping equipment has not
been observed. on Chinese ships, and the mine-
sweeping capability of the Chinese is believed to
be negligible against this type of mine. The
Chinese could provide the North Vietnamese with
trawler-type auxiliary minesweepers -- there are
40 to 50 of these craft in the South Seas Fleet,
south of Taiwan. China also has hundreds of
fishing trawlers in South China, including many
in the Tonkin Gulf area. Finally, the South China
Fleet has seven fleet minesweepers and four coastal
minesweepers. Even if China were willing to
transfer these units to North Vietnam, they would
be most effective against the MK-36 weapons, not
the MK-50. Once a decision was reached in Peking
to provide minesweepers -- of whatever kind --
the units could be on station in North Vietnam
within a few days. The Chinese would also have to
provide the manpower to operate these units because
North Vietnam lacks experienced seamen with the
technical competence for such operations.
7. Mine warfare has long been an important
part of Soviet naval strategy, and at the present
time the USSR possesses the world's largest stock-
pile of naval mines. Its current minesweeping
capability is equally impressive, involving the
use of almost 400 ships. The USSR has about 70
minesweepers at its Pacific Fleet naval bases,
primarily in Vladivostok and Petropavlovsk. These
ships are fitted to sweep acoustic mines, and it
is possible that a number of these craft and their
crews could be deployed into the upper Tonkin Gulf
for use in sweeping North Vietnamese minefields
within a week of the deployment decision.
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8. The effectiveness of a Soviet effort to
clear the Haiphong channel and the time required
for such an operation would depend on a number of
factors. First, the characteristics of the MK-50
would have to be determined by the Soviets so as to
make acoustic sweeping effective. With no prior
knowledge specific enough for operational use, this
could take several weeks, and possibly months.
Second, the precise area to be swept would have to
be determined. Finally, the ultimate size of the
minesweeping force and its schedule of operations
would be problems which could not be resolved until
the first two were decided. According to a US
minesweeping expert familiar with classified US
munitions, the achievement of a given probability
of clearing a mined area is a complicated and
sophisticated science, and the results of minefield
studies amount to only an educated guess or approxi-
mation. However, a minimum time frame can be set
because of the delayed arming capability of the
MK-50. A period of up to 90 days would be required
in order to clear completely a heavily mined area --
by which time, of course, a new set of mines could
have been implanted. It is quite possible that the
enemy might conclude that the only practical method
for clearing the coastal approaches to Haiphong
within any reasonable time, say a few weeks, would
be to employ unconventional methods such as dragging
operations using trawler nets. While this might
prove effective for limited areas in very shallow
water, the degree of success over wide areas of
water would be virtually nil.
Alternative Countermeasures
9. Facing up to the bleak prospect that mine-
sweeping takes time and would be of questionable
effectiveness, Hanoi would undoubtedly undertake
an intensive search for means of bringing in supplies
by alternate maritime means.* One such possibility
would be the use of lighters to offload ships in
unmined offshore areas. Lightering has been used
extensively in North Vietnam to speed up the off-
loading of ships in Haiphong port and to lighten
ships before they enter the port to decrease their
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The supply channel represented by overland
routes into North Vietnam would also almost cer-
tainly be greatly augmented.
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draft. The North Vietnamese have sufficient water-
craft to conduct extensive lightering operations --
a large portion of their inventory of river and
lightering craft normally operates in the Red River
delta region near Haiphong and would be readily
available. The efficiency of such operations, how-
ever, would be affected by a number of factors such
as the weather, the condition of the seas, and the
location of relatively safe or suitable anchorages
where merchant ships would be willing to drop
anchor. On the average, the seas in the northern
section of the Gulf of Tonkin are sufficiently calm
to permit lightering operations some 60 to 70 per-
cent of the time. The sheltered areas of the gulf
near the Ile Ca Ba provide protection from rough
seas, and, if not mined, would be the most suitable
area for offloading operation.
10. The North Vietnamese might also attempt
over--the-beach operations. Oceangoing ships could
anchor south of the Red River delta and offload
into lighters which could then move to southern
river ports, estuaries, and beaches. Such opera-
tions would be quite inefficient and would be
limited by difficulties in clearing cargo, particu-
larly from the beach areas where, presumably, there
would be only limited mechanized handling equip-
ment -- at best truck-mounted or floating cranes.
Nevertheless, this possibility cannot be dismissed
out of hand. From Thanh Hoa south to the DMZ there
are 27 beach areas that range from 500 yards to
38 miles in length. with a coordinated effort
between lighters and inland craft or trucks, it
would be possible to receive and move a large
volume of goods, assuming no US bombing.
Conclusions
. 11. The North Vietnamese have demonstrated that
they can cope with shallow magnetic mines of the
type effective against small coastal and inland
water craft, but the North Vietnamese themselves
would be unable to counter the heavier acoustical
mines effective against oceangoing ships. Both
the USSR-and Communist China possess minesweeping
fleets, but China probably does not have a capa-
bility against acoustical mines. There are some
70 Soviet minesweepers in eastern waters which
could be targeted against acoustical minefields
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within a few weeks time, although it could easily
take several months before the channels would be
completely secure.
12. Under such circumstances, Hanoi would un-
doubtedly seek other means of resuming the flow of
maritime imports. Lightering into unmined areas
is one possibility; over-the-beach operations
another. Neither of these techniques would be as
efficient as normal freight-handling procedures,
and both would be high-risk operations.
13. Hanoi's initial reaction to a US mining
program would probably be to make some probes
(:high-risk and necessarily primitive) to test the
minefields for weaknesses. With Soviet and/or
Chinese help, a more systematic countermeasures
program could be mounted within a few weeks.
While such minesweeping operations might enjoy some
limited success, Hanoi would probably soon deter-
mine that a sustained countering of a mining
program directed against oceangoing ships would
not be possible. Therefore, within the first
90 days (during which time North Vietnam's economic
and military reserves would be adequate without any
maritime resupply) an augmented overland supply
program would probably be organized.
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