203. Memorandum From Secretary of Defense Brown to President Carter 1

I attach a copy of a memorandum from the Joint Chiefs of Staff on (PD)/NSC–38, announcing your decisions as to the U.S. negotiating [Page 489]position on CTB. They have asked that I forward it to you, as an expression of their strongly held views. I believe that the JCS memorandum accurately identifies the technical and military factors involved. I agree with some, but not every one, of their evaluations.

A CTB involves some level of military risk. However, I believe that the probability that a CTB would adversely affect the reliability of the warheads for our important strategic systems is low enough during a three-year (or, less clearly, even a five-year) period so that for such a period the military risk in itself is acceptable. Of some weight also is the fact that we would become aware by continued stockpile inspection if a question of such reliability arises and, in principle, could invoke the supreme-national-interest withdrawal clause.

I emphasize that there would be a serious question of continued stockpile reliability on the U.S. side if there were an indefinite CTB.2 The greatest risk, therefore, follows from the tendency of a limited-term agreement to be extended. The statement of intention to resume tests at the end of a limited-term in order to assure stockpile reliability can somewhat ameliorate that problem. But the pressure at the time of expiration to renew (and also pressure not to do so) will probably be very great despite anything we say now. Such a concern about extension is likely to be expressed by opponents during the ratification process. This aspect, in my judgment, makes the prospects for approval of a CTB substantially less favorable than those for SALT, and also less favorable the earlier a CTB is concluded.

[1 paragraph (3 lines) not declassified]

I believe that the JCS paper understates the potential advantages from a CTB for non-proliferation (which many of us see as its main benefit). However, those advantages have yet to be articulated sufficiently. In my view it would be useful for the State Department and ACDA to set forth the criteria by which they believe we would be able to judge after a five-year period whether proliferation had indeed been inhibited by the CTB, and therefore whether there would be reasons supporting renewal to counter the military and technical needs for reliability tests.3

A great concern of mine is the possible irretrievable dissipation of our nuclear scientific and technological talent if a CTB is perceived by them as being of long or indefinite duration. To be able to test for stockpile reliability after a previously set time period of some years, and to correct deficiencies, the capabilities of the nuclear design laboratories [Page 490]have to be maintained. From this point of view there are two matters that particularly trouble me. (1) The decision to limit experiments to a few pounds4 of high explosive equivalent—rather than, for example, a few hundred tons5—limits sharply the degree of interest of such experiments to the scientists and technologists on whose continued skills and continued professional dedication to nuclear weapons design we would depend when tests are resumed. (2) Second, the five-year period of the treaty instead of a three-year period that had alternatively been proposed also reduces the chances of keeping viable nuclear laboratories together. The laboratory directors have told the JCS that, given a commitment to resume testing, they can maintain relevant laboratory effectiveness for three years, but probably not for five. I therefore urge that these two issues be reexamined as part of the development of the safeguards program you requested by June 30.6

Harold Brown


Memorandum From the Chairman of the Joint Chiefs of Staff (Jones) to Secretary of Defense Brown 7



  • Presidential Decision on Comprehensive Test Ban (U)

1. (S) Presidential Decision (PD)/NSC 388 announced that in view of the importance of maintaining confidence in safety and reliability of US stockpiled nuclear weapons, the President has decided that the United States should propose a fixed-duration Comprehensive Test Ban (CTB) treaty of 5 years, with provision for nuclear weapon experiments of a few pounds yield. In forwarding the treaty to the Senate for ratification, the President would state that the United States intends to resume testing at the expiration of the treaty, for safety and reliability purposes only, unless testing is shown not to be necessary. Any further [Page 491]agreement on testing limitations after the 5-year treaty would be presented to the Senate for ratification.

2. (S) The Joint Chiefs of Staff consider that the test ban, as outlined, would involve significant military risks. In a memorandum9 which you forwarded to the President on 22 April 1978,10 the Joint Chiefs of Staff stated they believe that a test ban must allow continued testing at a level sufficient to:

a. Maintain high confidence in the reliability of US nuclear weapons and hence confidence in the US nuclear deterrent.

b. Avoid undesirable asymmetries which are otherwise likely to result due to the inability of the United States to verify compliance with the test ban.

3. (S) Recent discussions which the Joint Chiefs of Staff have held with Department of Energy officials and their laboratory directors, upon whom the United States must rely for technical judgments concerning the reliability of US nuclear weapons, have further underscored the requirement for continued testing to maintain stockpile reliability. These experts have stated that, under a CTB with zero testing over an extended period, stockpile reliability will be degraded. They have taken the position that the most current nuclear warheads and bombs in the US stockpile cannot be maintained without nuclear testing. Their current best estimate is that the required nuclear yield for that purpose is at [less than 1 line not declassified] With nuclear testing permitted at [less than 1 line not declassified] it is likely that the current nuclear weapon stockpile could be maintained in a safe and reliable condition. The Joint Chiefs of Staff have found these assessments persuasive.

4. (S) Based on available information, Soviet reliability problems may not be as severe, since the Soviets’ typically heavier weapons and larger payloads have allowed them to use coarser design criteria which are not as susceptible to problems as the high-technology US designs. This is likely to cause an asymmetric degradation of the stockpiles. Assuming that the Soviets recognize this, they may eventually perceive a strategic advantage, and the asymmetry therefore would become destabilizing.

5. (S) The announced intention to restrict resumption of testing to that necessary for weapons safety and reliability appears to preempt decisions concerning weapons development which are better made in the context of other arms control agreements. The United States may be [Page 492]unilaterally restricting development of new strategic weapons, without any similar restraint upon the Soviets if a SAL agreement or other agreements reached do not restrict new strategic weapons development. Moreover, such an unfavorable asymmetry may also be imposed on the development of new theater/tactical nuclear weapons, at least until an arms control agreement with reciprocal restraints might be achieved.

6. (S) [10 lines not declassified] Thus, the United States will face a situation wherein the Soviets could test without detection and the United States will not test—a situation that could lead to asymmetries detrimental to the credibility of the US deterrent.

7. (S) Experience with the nuclear stockpile has demonstrated that serious problems can arise during a 5-year ban on nuclear testing. The decision in PD/NSC 38 does not provide for testing to address stockpile reliability problems which may arise during the period of the treaty. In the event that a serious problem arises, the United States would either have to exercise the “supreme national interest” withdrawal clause or depend on a less reliable deterrent force. The Joint Chiefs of Staff believe that, rather than accept the prospect of placing the United States in this undesirable situation, the United States should initially seek to negotiate a treaty which lowers the testing threshold to the level of verification capability. Such a lowered threshold could provide an opportunity to learn how to deal more confidently with stockpile reliability problems in an environment of restricted testing, while at the same time observing Soviet performance under the treaty and upgrading US monitoring capabilities.

8. (S) JCS discussions with the nuclear laboratory directors also have confirmed the belief of the Joint Chiefs of Staff that retention of skilled scientists and engineers at the US nuclear weapons laboratories is essential to maintain the stockpile and retain a nuclear weapons design capability. The Joint Chiefs of Staff concur with the judgment of the laboratory directors that it is unlikely that the necessary number of skilled scientists and engineers can be retained throughout a 5-year test suspension, even under the incentives of a strong safeguards program.

9. (S) In addition to the military and technical considerations expressed above, there are also politico-military implications which should be given consideration. The Joint Chiefs of Staff recognize that it is in the US national interest to stop nuclear proliferation. However, they are not at all certain the balance of considerations with respect to a test ban, as outlined, would contribute substantially to nonproliferation. Further, if US allies were to lose confidence in the ability of the United States to maintain a credible and reliable stockpile and, hence, in the deterrent quality of US nuclear guarantees, they could be disposed to develop or increase nuclear stocks.

[Page 493]

10. (S) The Joint Chiefs of Staff judge the military risks to national security to be serious. The issue is considered to be the adequacy of the US nuclear deterrent forces—both perceived and actual—and the equivalence of those forces to those of the Soviet Union. The magnitude of the risks and the potential consequences compel the Joint Chiefs of Staff to conclude that the negotiating position could result in a treaty which would adversely affect the national security interests of the United States.

11. (S) The Joint Chiefs of Staff request that you forward this memorandum to the President.

For the Joint Chiefs of Staff:

David C. JonesGeneral, USAF
Acting Chairman
Joint Chiefs of Staff
  1. Source: Washington National Records Center, OSD Files: FRC 330–81–0202, Box 53, A–400.112 TEST BAN (Apr–5 June) 1978. Secret. A handwritten “J” in the upper right-hand corner of the memorandum indicates Carter saw the document.
  2. In the right margin, Carter drew an arrow pointing to this and wrote “I agree.”
  3. In the left margin, Carter bracketed the portion of this paragraph that begins with “and ACDA set forth” and ends with “reliability tests.”
  4. Carter underlined the phrase “a few pounds.”
  5. Carter underlined the phrase “a few hundred tons.”
  6. Carter highlighted both point (1) and point (2) and wrote in the left margin “(1) I don’t feel strongly about this,” drawing an arrow pointing at the sentence for point (1), and “might help with this (2),” drawing an arrow pointing at the sentence for point (2).
  7. Secret. Brown wrote “5/30 HB” to the right of the memorandum number.
  8. See Document 200.
  9. Reference: JCSM–119–78, 18 April 1978, “Comprehensive Test Ban (U).” [Footnote is in the original.]
  10. See Document 193.