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178. Memorandum From the President's Assistant for National Security Affairs (Kissinger) to President Nixon 1


  • Enemy Manpower Situation in Vietnam

This memo summarizes the enemy's manpower situation and its strategic implications over the first six months of 1970.

The Enemy's Current Strength

The Washington intelligence community is in rough agreement that the enemy's current manpower situation is as follows:

  • —The enemy's military forces number about 280,000–310,000 men including at the most 150,000 main force regulars, 80,000 support troops, and 80,000 guerrillas.
  • —Despite heavy infiltration and recruiting, the enemy military forces have declined by about 28% (100,000 men) over the last two years with about half (40,000 to 50,000 men) of the decline occurring during 1969.

Enemy Losses

The enemy's manpower losses are caused by combat deaths, deaths caused by wounds or illness, desertions, and Allied captures. However, over the last two years, the enemy's overall losses, particularly [Page 561]combat deaths, appear to have been largely determined by the enemy's activity rates.

  • —When enemy activity is high, as during January–June 1968, the enemy's overall losses have run about 32,000 men monthly—20,000 combat deaths and 12,000 losses from other causes. By sustaining these losses, the enemy was able to initiate an average of about 470 attacks monthly.
  • —When enemy activity is moderate, as during January–June 1969, the enemy's overall losses have averaged about 27,000 men monthly— 16,000 in combat deaths and 11,000 from other causes. At this manpower cost, the enemy was able to launch about 370 attacks monthly.
  • —When enemy activity is low, as during June–December 1969, the enemy has been able to hold his overall losses to about 20,000 men monthly equally divided between combat and non-combat losses. During this period, enemy-initiated attacks averaged 233 monthly.

Thus, the enemy has, to a large extent, been able to control his losses by increasing or decreasing the aggressiveness of his forces. While there is no real limit on these fluctuations in enemy losses, the enemy probably considers that a certain level of activity is necessary to maintain the momentum of his war effort and his control of a portion of SVN's population. Moreover, allied-initiated operations undoubtedly impose certain losses on the enemy as the price for retaining his forces in South Vietnam even if they are inactive.

For these reasons, it is likely that there is some minimum level of losses that the enemy will either choose or be forced to sustain. Looking at enemy losses during past periods of low activity, this minimum loss rate may be about 20,000 men monthly, including 10,000 combat deaths.

Enemy Manpower Gains

The enemy meets its manpower requirements from two principal sources—infiltration and recruitment. Judging from recent experience, the enemy can count on these sources of manpower to provide replacements at the following rates:

  • Infiltration will provide most of the enemy's manpower gains. While only about 15,000 infiltrators will arrive in South Vietnam during January–March 1970, the enemy increased its manpower in the pipeline to South Vietnam by about 15,000 men in January alone. If additions to the pipeline continue at this rate, the enemy could infiltrate 60,000 men into SVN during the first six months of 1970.2
  • Recruitment. While the enemy is capable of increasing his recruiting in SVN for a short period of time, his recruiting rates have been low (4,000 to 6,000 men monthly) in recent months and he may not be able to increase them greatly without a strong and successful effort to increase the population he controls and the recruiting base it affords. Without such an increase, the enemy cannot count on more than about 36,000 new recruits during the first six months of 1970.

If recruitment and infiltration follow this pattern, the enemy will add about 100,000 men to his military forces during this period. However, these additions will enable the enemy to offset his likely losses only if he maintains a low rate of activity. If the enemy maintains a moderate or high rate of activity, his losses will more than outnumber his manpower gains and the overall strength of his forces will continue to decline.

Thus, even with the recent increase in infiltration, the enemy probably cannot build-up his forces unless he decreases his activity below the lowest levels of the recent past or greatly increases recruiting.

Future Enemy Options

The current enemy manpower situation is not bright. If recent trends in infiltration, recruiting, and losses continue, the enemy will continue to suffer a slow attrition in the strength of his military forces. However, this decline is not inevitable and the enemy could build-up his forces if he chose to. In particular, he could:

  • —Reduce his activity to a virtual standstill (10,000 losses monthly) while maintaining an infiltration rate of about 15,000 men monthly. By June 1970, the enemy might be able to increase his force level by about 30,000 men by June 1970.
  • —Step up infiltration to 25,000 men monthly, as during early 1968, while maintaining his present low activity rates. By June 1970, the enemy's forces could be increased by 30,000 men.

However, these strategies would not allow the enemy to carry out a countrywide offensive for longer than a month without suffering some reduction in his force strength. For instance, the enemy losses in combat deaths alone were almost 40,000 men monthly at the height of the 1968 Tet offensive. An offensive confined to a particular region such as the Delta would, however, require far smaller inputs of manpower and be more reasonable given the enemy's manpower resources.


To maintain his force levels, the enemy will have to continue infiltration at its January rate of 15,000 men monthly while holding his activity to the low rates of late 1969. By further increasing infiltration or greatly reducing activity, the enemy could build-up his force levels for an offensive by June. However, the most likely prospect is that the enemy's force strength will continue to slowly decline.

  1. Source: National Archives, Nixon Presidential Materials, NSC Files, Country Files, Vietnam, March 1970. Secret; [codeword not declassified]. Sent for information. In a February 5 covering memorandum Lynn informed Kissinger that this summary was done by John C. Court of the NSC's Program Analysis Staff based on the Vietnam Special Study Group Enemy Capabilities Panel's report. Lynn recommended that the summary be sent to the President. A note on the memorandum indicates it was “ret-d, Feb. 20, 1970.” The VSSG's report, “A Review of Enemy Manpower Indicators in the War in Southeast Asia” SC 14685/69, December 1969, is ibid., Haig Special Files, Vietnam File, Vol. 4 (Jan–Feb, 1970) [2 of 2].
  2. Attached but not printed was an undated explanation of infiltration estimates which indicated that they were “based largely on intercepts of uncoded enemy rear area communications” which “frequently provided detailed information on the number, strength, and destination of enemy infiltration groups.” Collateral evidence such as prisoner interrogations and captured documents verified this intelligence. Since the primary evidence was uncoded, it could be misleading if the North Vietnamese were aware of the fact that they were being intercepted. Furthermore, rear services communications did not cover all infiltrators, and if North Vietnam chose, they could infiltrate large units using radio silence.