Date

Dec 3, 1964

Description

Rejecting minimum deterrence, McNamara eventually supported a Minuteman force of 1000 as a compromise with the Air Force, which had wanted much more. Nevertheless, several years later, and perhaps remembering the briefing on Polaris, McNamara hinted that a small nuclear force was sufficient for the basic deterrence mission of "assured destruction," which was a term that he and his advisers developed for sizing strategic force levels. In a Draft Presidential Memorandum (DPM) sent to President Johnson in late 1964, McNamara defined an assured destruction force as one that could destroy 25 percent of the Soviet Union's population and more than two-thirds of its industrial capacity. That was a "level of destruction [that] would certainly represent intolerable punishment to any industrialized national and this should serve as an effective deterrent" (p. 4).

Several pages later, during a discussion of the "destructive potential of various size U.S. attacks on Soviet cities," McNamara observed that a force of 400 strategic weapons was enough to destroy "nearly 30 percent of the population of the entire nation" and "almost three-fourths of the industrial capacity of the Soviet Union." In other words, a force of 400 was sufficient to achieve the "assured destruction" mission. Doubling the number, to 800, would only produce marginal benefits.

The experience of the Cuban Missile Crisis, among other considerations, may have encouraged McNamara think along those lines. When President Kennedy and the "ExCom" learned that the Air Force could not guarantee that a U.S. air strike could destroy all Soviet missiles in Cuba, the prospect that even one missile would survive was enough to deter the United States from taking military action against the missile sites. In any event, McNamara drew no explicit policy conclusions from his brief discussion of 400 weapons; he may not have seen that as plausible for deterrence because elsewhere in the DPM he supported a "balanced" nuclear force that included some damage limiting capability. Nevertheless, over the years his thinking shifted and by the 1980s, if not earlier, McNamara supported a concept of deterrence that echoed earlier Navy thinking. In 1986, he wrote that "five hundred or fewer warheads" were sufficient for deterrence. Perhaps forgetting his earlier rejection of finite deterrence, McNamara wrote that he had learned, from reading David Rosenberg's work, that "in 1958 and 1959 the Navy had put forward such a plan."[27]

Source

FOIA release; DNSA

Document published in following posting(s):

"How Much is Enough?": The U.S. Navy and "Finite Deterrence"

Oct 14, 2021

"Intolerable Punishment to Any Industrialized Nation"Memorandum from Secretary of Defense McNamara to President Johnson, "Recommended FY 1966-1970 Programs for Strategic Offensive Forces, Continental Air and Missile Defense Forces, and Civil Defense," 3 December 1964, Top Secret, Excised copy