22. Memorandum From Laurence E. Lynn, Jr., of the National Security Council Staff to the President’s Assistant for National Security Affairs (Kissinger)1


  • U.S. Force Reductions in Thailand

I understand proposals to reduce U.S. strength in Thailand by 7,000 and 10,000 are under consideration.

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It is also my understanding that CINCPAC proposes to accomplish the reduction with the following withdrawals.

7,000 man reduction 10,000 man reduction
2 A–1 squadrons Same as for 7,000, plus:
1 A–26 squadron 3 F–105 squadrons and related support units
2 EB–66 squadrons plus related support units

These CINCPAC proposals raise important questions regarding the role of the remaining U.S. forces in Thailand. CINCPAC is proposing to take out virtually all of those forces best suited for missions over Laos (to assist the Laotian government and to bomb the Ho Chi Minh Trail), leaving in Thailand the forces best suited to bomb North Vietnam and clearly inferior for Laotian missions.

There are now 16 “fighter/attack” squadrons in Thailand. Twelve of these are high-performance jet squadrons (8 with F–4s; 4 with F–105s). Four are equipped with propeller-driven aircraft (3 with A–1s; one with A–26s).

Either CINCPAC proposal would remove all but one propeller squadron (which would remain primarily for search and rescue operations). According to available evidence on the comparative efficiency of these versus high performance jets, this would be a very poor allocation of our resources in Thailand.

Comparison of the effectiveness of jet aircraft and propeller-driven airplanes in attacking ground targets in Southeast Asia has shown that the prop planes are considerably more efficient than the jets. A recent study (August 1969) indicates that in Laos in 1968 propeller-driven aircraft were roughly twice as effective as jets in terms of targets destroyed per attack.

Comparison of Targets Destroyed or Damaged per 100 Attacks
Prop Planes Jets
Target Type A–1 A–26 F–4 F–105
Trucks 46.8 49.0 23.0 18.5
Truck Parks 3.4 5.2 2.5 1.9
Roads 53.6 55.0 25.9 23.3
Logistics Storage Areas 13.2 N/A 6.6 6.8
Air Defense Targets 12.6 12.9 8.3 12.7

Furthermore, the costs per year per squadron are substantially less for prop squadrons compared with jet squadrons.

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Total Southeast Asia Operating Costs per Squadron per Year Prop Jet
A–1 A–26 F–4 F–105
$41 m $30 m $56 m $61 m

The primary combat advantage of the prop aircraft is their ability to loiter, locate a target, and make multiple attacks on it. (Jets have a comparative advantage against sophisticated defenses, but these are not an important factor in Laos.) Prop aircraft also perform as well at night as during the day,2 while jets are only half as efficient after dark. Most of the targets appear at night. One study has shown that the cost of destroying a target at night with a jet is 13 times greater than with a propeller aircraft. Finally, prop aircraft losses per target destroyed are about the same or lower than for jets.

Considering this evidence, it is hard to fathom CINCPAC’s rationale for their proposed force cuts. An alternative proposal to take out three more jet squadrons instead of the A–1s and A–26s would provide more manpower reductions, considerably larger budgetary savings, and would have the least impact on the war effort. The disadvantage in doing so is that if bombing of North Vietnam were resumed jets would be preferable. Nevertheless, even an all jet redeployment would leave six squadrons of high-performance jets in Thailand, and if we decide to bomb North Vietnam again we can redeploy additional jet squadrons as necessary.

The proposal recommended by CINCPAC demonstrates again our inclination to attempt to suit the war to our equipment and technological preferences rather than the other way around. Our policies in this respect also serve to indicate to our allies that high-performance jets are better counter-insurgency aircraft than props, when in fact the reverse is true.

  1. Source: National Archives, Nixon Presidential Materials, NSC Files, Box 560, Country Files, Far East, Thailand, Vol. I. Secret. Sent for information. Printed from an unsigned copy.
  2. It has been suggested that the reason the effectiveness of prop aircraft does not decline at night is that the enemy cannot make visual sightings at night, there is more truck traffic at night, and the enemy’s visually targeted anti-aircraft weapons are less effective at night. These factors permit the low flying, slower prop aircraft to operate more effectively whereas the high-speed jet cannot operate at low altitudes at night without greatly increased risks. [Footnote in the source text.]