117. Memorandum From the Assistant Secretary of Defense for Systems Analysis (Enthoven) to Secretary of Defense McNamara 1


  • Programmed Future Strategic Ballistic Missile Force Capabilities (U)

Enclosed is a summary table drawn from an evaluation of the programmed U.S. missile force against likely estimates of the future Soviet target system. These estimates are based upon the median estimates of this threat presented in the N.I.E. on Soviet capabilities for strategic attack (N.I.E. 11–8–65).2 Enclosed also are tables containing the detailed assumptions for the analysis. Most of the previous calculations that you have seen for this time period have treated the U.S. Assured Destruction capability in the face of a maximum plausible Soviet threat. By contrast the enclosed calculations are relevant to the U.S. combined Assured Destruction/Damage Limiting capability against a more likely Soviet threat. These calculations strongly suggest that U.S. capabilities to attack the likely Sino-Soviet target system will increase sharply over the period 1966 to 1971. By 1971 our ballistic missile force alone, operating in pre-emption, would be able to destroy the major part of their strategic offensive forces. To compare the 1971 force with the current force, we have assumed that [8–1/2 lines of source text not declassified]. In terms of residual opposing weapons, instead of average kill against the target systems, the performance is even more impressive. When bomber weapons are also included in U.S. counter-military strikes, this effectiveness would be further enhanced.

The calculations summarized above utilized a targeting procedure as much like that of the SIOP as we could make it. We used a median threat without ABMs or extremely high numbers of Soviet hardened missiles to test the ability of our missile forces to destroy military targets for the Damage Limiting mission. We are now in the process of calculating performance when targeting is designed to minimize Soviet damage potential, instead of following [2 lines of source text not declassified].

[Page 354]

I expect to use the calculations in this paper in the next Presidential Memorandum on Strategic Offensive and Defensive Forces, and compare the results with others that assume larger missile forces withheld for the urban-industrial task. Additionally, since the results are so striking, a copy of the enclosed table has been made available for the back-up book for your congressional testimony. I will, of course, send you the full paper if you are interested in pursuing this any further.

Alain Enthoven




[table (6 columns and 12 rows) not declassified]



1966 1967 1969 1971
Minuteman I 800 700 400 100
Minuteman II 80 300 550 600
[*] [*]
Minuteman III 0 0 50 300
Titan II 54 54 54 54
Polaris A2/A3 (66% At Sea) 512 656 656 656

[* number and text in table not declassified]

[Page 355]



SIOP–4 1967
Non-Reprog. Rel.3 CEP Non-Reprog. Rel. CEP Yield
Minuteman I [*] [*] [*] [*] [*]
Minuteman II [*] [*] [*] [*] [*]
Minuteman III [*] [*] [*] [*] [*]
Titan II [*] [*] [*] [*] [*]
Polaris A2/A3 (66% At Sea) [*] [*] [*] [*] [*]
1969 1971
Reprog Rel Non Reprog Rel. CEP Reprog Rel. Non Reprog Rel. CEP Yield
System [*] [*] [*] [*] [*] [*]
Minuteman I [*] [*] [*] [*] [*] [*] [*]
Minuteman II [*] [*] [*] [*] [*] [*]2 [*]
Minuteman III [*] [*] [*] [*] [*] [*]2 [*]
Titan II [*] [*] [*] [*] [*] [*]
Polaris A2/A3 (66% At Sea) [*] [*] [*] [*] [*] [*] [*]

[* entry in table not declassified]




[table (13 columns and 10 rows) not declassified]

  1. Source: Washington National Records Center, OSD Files: FRC 330 70 A 4662, 381 SRF 1966. Top Secret. A stamped notation, dated April 6, reads: “Sec Def has seen.”
  2. Document 97.
  3. All reliability estimates are from Blue Lance.
  4. Non-Reprogrammable Reliability. Reprogramming of missiles for unreliability is an operation in which new missiles are assigned and launched to cover the targets of missiles that have failed in launch. The amount of the total unreliability for which reprogramming is possible depends on the stage in missile flight at which success or failure is reported (e.g., lift-off or cut-off). Non-reprogrammable reliability is the reliability of the missile after the last report.
  5. BSD Estimates of operational CEP.
  6. BSD Estimates of operational CEP.