Foreign Relations of the United States, 1964–1968, Volume XXVIII, Laos

337. Memorandum From the Joint Chiefs of Staff to Secretary of Defense McNamara ¹

JCSM–129–68

Washington, February 29, 1968.

SUBJECT

• The Use of Propeller and Jet Aircraft in Laos (U)

1. (U) Reference is made to your memorandum, dated 25 January 1968, subject as above.²

2. (TS) Air strike forces in Southeast Asia require a mix of types of aircraft to perform with optimum effectiveness in both the unsophisticated air defense environment found in Laos and South Vietnam and the heavily defended area of North Vietnam. Reduction of the flow of materials to South Vietnam is more effectively achieved by striking as close to the source as possible. It is, of course, essential to keep these materials under attack throughout the infiltration system. Whenever the choice exists, however, the primary emphasis must be to stop or destroy this equipment before it is dispersed throughout the maze of highways, roads, and trails in North Vietnam and Laos. To attack at the source requires a force that can operate in the highly defended areas of Hanoi and Haiphong at maximum strength. Specialized forces, which can survive only in relatively undefended areas, should be in addition to, not as a substitute for, the force capable of striking the source. Any reduction of the existing F–4 force in Southeast Asia would materially limit the ability to strike the supply source. Therefore, the total mission objective in Southeast Asia should be considered when structuring the force mix to optimize capabilities in the different defense environments.

3. (TS) Both the OSD study and the 18 December 1967 7th Air Force “Comparative Analysis of Propeller vs Jet Aircraft”³ are addressed to a comparison of propeller aircraft and jet aircraft. However, a more proper comparison is between low and high wing-loaded aircraft. Low wing-loaded jet aircraft such as the B–57 and A–37 have performance characteristics more closely aligned with the low-level/permissive environment capabilities of the A–1, A–26, and T–28 than with the characteristics of the F–4 and F–105. In further discussion in this paper, this comparison is made instead of the more simple but less correct comparison between propeller and jet aircraft. An analysis of the relative effectiveness of low wing-loaded versus high wing-loaded aircraft operations against trucks in Laos should consider: (a) general aircraft capabilities (Appendix A); (b) type mission executed (Appendix B); (c) amount of effort which is applied against trucks (Appendix A); and (d) a comparison of aircraft vulnerability within its area of operations (Appendix C). Comments on these factors are included in the Appendices hereto.⁴

4. (TS) With respect to improvements, maximum use is being made of road watch teams, electronic sensors, and night observation devices, i.e., Starlight Scope, side-looking infrared radar, and low light-level television, to improve the probability of detecting vehicles, waterborne craft, and personnel. The development of a suitable anti-vehicle mine and improved area ordnance for high-performance jet aircraft is receiving priority attention. Gunship II should further contribute to this program.

5. (TS) The requirement for a balanced force mix in Southeast Asia and additional considerations contained in the Appendices support the following conclusions:

a. Low wing-loaded aircraft also have demonstrated high effectiveness in the night route interdiction mission in a relatively permissive defense environment. However, employment in highly defended areas is precluded because of vulnerability.

b. High wing-loaded aircraft provide an excellent capability against the total Southeast Asia environment. If these aircraft were assigned the primary task of truck interdiction, their relative effectiveness against this target element would improve. However, the existing F–4 force is the minimum required to accomplish effectively the overall mission. Any reduction or diversion of this force would proportionately reduce the capability that can be applied against the most critical points of the enemy’s supply distribution system: Hanoi and Haiphong.

c. The interdiction effort in Laos is a team effort. The extensive daylight jet strikes against truck parks, transfer points, roads, and supply depots force enemy trucks to travel almost exclusively at night. This has improved the target opportunity and, consequently, the effectiveness of night operations of low wing-loaded aircraft. This balanced approach to interdiction would be adversely affected by substitution of A–1 for F–4 squadrons. Therefore, the aircraft approved for deployment in Program 5 should be additive to, not a substitution for, F–4 assets in Southeast Asia.

6. (TS) Based on these conclusions, the Joint Chiefs of Staff recommend that the proposed substitution of A–1 for F–4 squadrons suggested in the OSD study be removed from further consideration.⁵

For the Joint Chiefs of Staff:

J.O. Cobb
Rear Admiral, USN
Deputy Director, Joint Staff

1. Source: Washington National Records Center, RG 330, OSD/Admin Files: FRC 73 A 1304, Laos 385.1, 1968. Top Secret.
2. See footnote 8, Document 326.
3. See the enclosure to Document 323.
4. The appendices are attached, but not printed.
5. In a March 8 memorandum to McNamara, Assistant Secretary of Defense Alain Enthoven disagreed with “both the logic and recommendations” of this JCS paper, but since the Air Force was including an increase from 61 to 97 A–1 aircraft in its proposal to deploy 270 additional fighter/attack aircraft, the issue was overtaken by events. (Washington National Records Center, RG 330, OSD/Admin Files: FRC 73 A 1304, Laos 385.1, 1968)