Foreign Relations of the United States, 1964–1968, Volume XI, Arms Control and Disarmament

147. Report Prepared by a Panel Appointed by the Arms Control and Disarmament Agency¹

Washington, September 2, 1966.

REPORT OF THE ACDA PANEL ON SECURITY IMPLICATIONS OF MODIFYING VARIOUS AGREEMENTS TO BAN NUCLEAR WEAPONS TESTS WHILE PERMITTING EXPLOSIONS FOR PEACEFUL PURPOSES

[Here follows a table of contents.]

I. Introduction

The Panel to examine the security implications of modifying various agreements to ban nuclear weapons tests while permitting explosions for peaceful uses² was convened at the request of the Arms Control and Disarmament Agency. The Panel was requested to address itself to the following questions.

a. What types of weapons development or effects tests could be carried out as part of legitimate or defendable peaceful uses explosions programs within the terms of a limited, a threshold and a comprehensive test ban treaty?

b. What would be the probability of verifying that no illegal weapons development or effects tests were carried out as a part of a peaceful uses explosions program?

c. What is the military significance of developments which might be carried out under “a.” above and by illegal means?

d. What types of verification arrangements could be incorporated in such treaties in order to reduce to acceptable levels the risk that U.S. security might be compromised by development under “a.” and “b.” above?

The Panel met in Washington on June 28, 1966; in Livermore, California, on July 14, 1966; in Los Angeles on July 30, 1966; and in Washington on August 21, 1966 to examine these questions and to receive information on the status of U.S. and USSR Plowshare and weapons test programs. Particular attention was paid to techniques for carrying out actual nuclear weapons tests. Sub-groups of the panel also met to examine various more specialized problems associated with the topic.

It was not a function of the Panel to evaluate the usefulness of specific projects for peaceful uses of nuclear explosions or the value of such programs as a whole; likewise it was not a function of the Panel to evaluate the merits or demerits of specific test ban proposals per se, except insofar as additive provisions to such test ban proposals relating to peaceful uses explosions might provide opportunities for obtaining weapons development or weapons effects information, or contribute to the proliferation of nuclear weapons technology. Consequently it should be made clear that, although our report contains numerous definite conclusions, it does not contain recommendations for or endorsements of either specific test ban proposals or specific projects relating to the peaceful uses of nuclear weapons.

The Panel would like to express its appreciation for the cooperation received from ACDA and from the AEC staff and its laboratories, particularly from the Livermore Laboratory.³

II. Conclusions

This Panel was charged with analyzing the implication of a Plowshare annex to various forms of nuclear test ban treaties.

In the conclusions to follow we interpret the term “annex” to mean an addition to the treaty that would provide for a declaration of purpose of a peaceful uses explosion combined with some kind of approval mechanism and that would permit observers with specified duties and powers to attend the operation. In addition to these general provisions, possible annexes might, for example, restrict the yields available to a Plowshare detonation or require that explosive devices be placed at an early specified time in a warehouse.

We have assumed that disclosure of the device would not be permitted to other nuclear-weapons-powers or non-nuclear-weapon-powers. Disclosure to the latter would reveal weapon technology, and disclosure to the former raises serious and difficult problems of national security.

The US has agreed to the present limited test ban in the hope of retarding the development and diffusion of military nuclear explosive technology. In the absence of a Soviet “open society,” a basic policy of the US Government toward any arms control agreement is that it be adequately verified so as to give reasonable assurance that U.S. security interests are protected.

While we see little incompatibility between a Plowshare annex and the limited restrictions on weapons development imposed by the present Limited Test Ban Treaty (LTBT), the basic question faced by this Panel centered around whether this policy of verification on the one hand and full development and exploitation of nuclear explosions for peaceful purposes on the other are compatible with further tightening of the test ban limitations. Our conclusion is that the answer to this general question is “no,” primarily since even with an extensive observer program it is not possible to assure that the basic data needed for military device development are not being obtained in a given Plowshare operation. However, a more limited Plowshare program excluding excavation may be compatible with a further extension of the LTBT.

In further detail we submit the following conclusions:

1. To the extent that Plowshare annexes of the types considered by the Panel extend the yields and types of tests permissible under the test ban treaty, they correspondingly open the possibility of some important weapons device development being carried out as part of Plowshare operations, and to an even greater extent in connection with tests for the development of Plowshare explosives.

2. It is possible through observers of a Plowshare operation to restrict severely the acquisition of diagnostic data on specialized device outputs or on weapons effects tests, depending upon the number of observers, their tools and their degree and duration of access. Achievement of an adequate observer program may be a serious negotiation problem.

3. Plowshare activities under any treaty annex would not make a technical contribution to the proliferation of nuclear weapons to non-nuclear nations unless (a) the annex provided for disclosure of the design of the devices used or for their inspection, (b) the declaration of purpose or the permitted activities of the observers would reveal nuclear device design information, or (c) the annex allowed the development or detonation of nuclear explosives by non-nuclear nations.

4. If a Plowshare annex were to be added to the present LTBT the military potential of the nations now subscribing to the treaty would not be substantially affected in view of the large flexibility in terms of nuclear tests allowed under the present treaty. Although an excavation program permitted by a Plowshare annex is compatible with the restrictions on weapons development imposed by the LTBT, such an annex would set a serious precedent which could be incompatible with future more restrictive test bans.⁴

5. A Plowshare annex to a seismic threshold test ban treaty (TTBT) that permitted an extensive Plowshare program would have the effect of circumventing the yield threshold for weapons development. A Plowshare annex based on a yield limit for explosions in hard rock corresponding to the yield legal in “soft” media under a TTBT could permit some underground engineering activity. If the annex permitted in effect a substantial increase in the nuclear test yield, then, for example, the impediment that a threshold test ban provided toward further development of area defense anti-missile warheads could be circumvented. In addition, the annex would leave the option open for Soviet Union developments in lighter-weight strategic warheads of high yield-to-weight ratio that would contribute to a MIRV development. Particularly serious is the loophole made possible by a Plowshare annex that would permit a few high-yield weapons development tests that could culminate illegally a series of lower-yield tests carried out legally under a threshold test ban treaty. These “loopholes” provided by the annex could have exceedingly serious consequences for the U.S. deterrent if the Soviet Union chose this means of evasion.

6. Under a comprehensive test ban treaty (CTBT), a Plowshare annex would in effect decrease the “comprehensiveness” of the treaty by permitting, even in the absence of explicit evasion, continued nuclear device development over a wide range of yields and proof testing of the stockpile, and by maintaining the vitality of nuclear weapons establishments. The ability to maintain the vitality of the weapons establishments of both the U.S. and the USSR would make the asymmetry through possible Soviet cheating under a CTBT less significant than if no Plowshare program were permitted. However, an annex permitting an extensive Plowshare program,⁵ including excavation, would make possible weapon developments as discussed in Para. 5 above and also would add weapon development possibilities below the threshold. These loopholes, if used by the Soviet Union and not by the U.S. could have highly damaging military consequences. Such an annex adds extensive evasion possibilities to the limited evasion possibilities available without an annex.

[Here follow Sections III-V of the report entitled “Nuclear Test Requirements for Plowshare Modifications of Various Test Ban Treaties,” “The Evasion Possibilities and the Possible Plowshare Modifications of Various Test Ban Treaties,” and “Military Significance of the Nuclear Test Program Possible Under Plowshare Modifications of Various Test Ban Treaties,” respectively, and Appendix A, “Examples of Peaceful Uses and Nuclear Explosive Requirements.”]

1. Source: Department of State, S/AL Files: Lot 67 D 2. Secret; Restricted Data. The source text has two cover memoranda: the first from Larry Williamson (S/S-S) to Llewellyn Thompson (S/AL), et al., September 6, transmitting the report. The second from William C. Foster to the members of the Committee of Principals, September 2, transmits the Ad Hoc Panel’s Report and explains the origins of the Panel as follows: “at the meeting of the Deputies to the Committee of Principals held on June 3, 1966, serious questions were raised about the possibilities of evasion of a Threshold Test Ban Treaty through provisions for nuclear explosions for peaceful purposes. As a result ACDA organized a panel of experts consisting of Dr. Richard Blankenbecler, Dr. Warren Heckrotte, Mr. William J. Howard, Dr. William G. McMillan, Dr. Theodore B. Taylor, and Dr. M. Carl Walske under the chairmanship of Dr. Wolfgang K.H. Panofsky to study the security implications of modifying various agreements to ban nuclear weapons tests while permitting explosions for peaceful purposes.”
2. Throughout the report the terms “Plowshare” and “peaceful uses” are used synonymously; and therefore the first term should not be interpreted as limited to the present U.S. program. [Footnote in the source text.]
3. The LRL report “Technical Relation Between Plowshare and Weapons Programs Under Various Nuclear Test Ban Treaty Proposals” by G. Werth and W. Heckrotte, dated August 1, 1966, was made available to the Panel. [Footnote in the source text; a copy of this Livermore Radiation Laboratory report is attached to a September 6 cover memorandum from T.R. Shaver (S/S-S) to Johnson (G), et al. in Department of State, S/AL Files: Lot 67 D 2.]
4. Dr. Heckrotte believes that an evaluation of a Plowshare annex to the LTBT as a “serious precedent” involves value judgments of Plowshare and test ban treaties dependent on technical, economic, and political factors, most of which were not within the purview of this Panel. [Footnote in the source text.]
5. Dr. Heckrotte believes that some attention should be given to the possibilities of accommodating a limited Plowshare program to more restrictive test bans. This could avoid risks which would be introduced at this time by an annex to more restrictive test bans which permitted an extensive Plowshare program; for example, see pages 14 and 16 and also the LRL report mentioned on page 4. [Footnote in the source text.]