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7 Nuclear Test Bans INTRODUCTION The banning of nuclear testing has been a central and continuing objective of arms control since the mid-19SOs. At the end of the Eisen- hower and beginning of the Kennedy administrations, the United States and the United Kingdom made a major effort to negotiate a comprehensive test ban (CTB) treaty with the Soviet Union. Although these trilateral negotiations failed to produce a comprehensive test ban, agreement was finally reached in 1963 on the :Limited Test Ban (LTB) Treaty (Appendix D), which banned all nuclear tests except those con- ducted underground. In 1974 the Nixon Administration negotiated the Threshold Test Ban (TTB) Treaty (Appendix E), which banned under- ground tests above 150 kt; and in 1976 the Ford Administration negoti- ated the companion Peaceful Nuclear Explosions (PNE) Treaty (Appendix F), which provided for the special handling of peaceful explo- sions under the threshold. The Carter Administration renewed the ef- fort to negotiate a comprehensive test ban treaty but failed to produce an agreement. The Reagan Administration has taken the position that, while a comprehensive test ban remains a Tong-term U.S. goal, such a treaty would not be in the security interests of the United States at the present time. BACKGROUND The Eisenhower Administration By the mid-1950s, public opposition to nuclear testing had become a significant domestic and international political force. The recurring 187

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188 NUCLEAR ARMS CONTROL U.S. and Soviet nuclear test series, involving growing numbers of explo- sions with rapidly increasing yields, were a constant reminder of th threat and consequences of nuclear war. With the unexpected discovery of the extent of the danger of fallout during the U.S. test series in 1954, nuclear testing was also widely seen as a direct threat to public health and safety. Early proposals to stop testing were opposed within the U.S. government by both military and civilian officials on the grounds that the requirements for more advanced nuclear weapons were so urgent as to far outweigh any immediate health dangers that might be associated with nuclear tests. Questions were also raised about the ability to verify a ban on nuclear tests. In early 1958' following a major Soviet test series, the Soviet Union seized the political initiative by announcing that it would stop testing unilaterally if the United States would do likewise. In a major policy shift in the spring of 195S, President Dwight Eisenhower proposed to Soviet Secretary Nikita Khrushchev that sci- entists from the two sides meet to assess the verifiability of a ban on nuclear tests and to recommend a possible control system. In addition to political concern about the mounting international opposition to test- ing, President Eisenhower's decision reflected the advice of the newly formed President's Science Advisory Committee under James Killian. Challenging the positions of the Department of Defense and the Atomic Energy Commission, the committee advised the President that a test ban could be monitored and would be in the security interests of the United States given the relative status of the nuclear weapons pro- grams of the two sides. The Conference of Experts, which was held in Geneva, Switzerland, during the summer of 195S, brought together a remarkable group of outstanding scientists and specialists on nuclear test detection from the West (the United States, the United Kingdom, France, and Canada) and the East (the Soviet Union, Poland, Czechoslovakia, and Romania). The conference, which was conducted as a technical study and not as a political negotiation, examined the technical problems of monitoring nuclear tests in the atmosphere, in the oceans, and underground. The report of the conference found that an international control system, using available techniques and on-site inspection, would "make it pos- sible to detect and identify nuclear explosions, including Tow-yield ex- plosions (1-5 kt)." The proposed system would have been a worldwide network made up of some 160 to 170 land-based manned control posts and ten ships with appropriate instrumentation. Subsequently, it was agreed in a separate technical working group that the control system could also be applied to tests in space if satellite-borne detectors were incorporated into it.

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NUCLEAR TEST BANS 189 On the basis of the findings of the Conference of Experts, President Eisenhower called for formal negotiations on a comprehensive test ban. At the same time he announced a one-year moratorium on all testing provided the Soviet Union did the same. This moratorium was subse- quer~tly extended to the end of 1959 and testing was not resumed until 1961. On October 31, 195S, the United States, the Soviet Union, and the United Kingdom, then the only nuclear powers, opened the Conference on the Discontinuance of Nuclear Tests in Geneva, Switzerland. Despite the technical agreement at the Conference of Experts, the political negotiators quickly found that the sides were far apart in defining how the control system would actually operate and how on-site inspections, which were supposed to resolve questions regarding unidentified events, would be conclucted. The United States and the United Kingdom envisaged a system administered by international personnel and oper- ating by a majority vote, while the Soviet Union insisted on a system that it could control within its own borders. The United States soon complicated the negotiations further by intro- ducing new technical data and new technical problems that brought into question the findings ofthe Conference of Experts. The U.S. delega- tion first reported that analyses of new data from U.S. underground tests conducted after the Conference of Experts indicated that the Tow- est seismic yield that could be iclentified as an earthquake was about twice as high as that originally estimated. More significantly, the U.S. delegation then reported that new studies revealed a number of tech- niques that could permit a violator to conduct relatively large-yield underground tests so that they would not be identified or even detected by the proposed control system. The most striking of the clandestine testing techniques was the con- cept of testing in huge underground cavities. Such cavities were calcu- lated to be capable of decoupling the seismic signal from a nuclear explosion by a factor of 100 or more. The United States also suggested the possibility of conducting tests during very large earthquakes to bury the seismic signal from the test in the much greater signal from the earthquake. The Soviet delegation rejected these technical develop- ments as simply efforts to prevent agreement. In the United States, opponents of the test ban in the executive branch and Congress seized upon the technical developments as conclusive proof that a comprehen- sive ban could not be verified. The U.S. government initiated an exten- sive research and development program (Project Vela) directed at improving seismic monitoring and other verification capabilities. In an attempt to bypass the increasing controversy over the verifica- tion of underground tests, the Eisenhower Administration proposed to ban only those tests that could be verified by the control system devised

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190 NUCLEAR ARMS CONTROL by the Conference of Experts. Early in 1960 the United States intro- duced a draft threshold treaty that would have banned all atmospheric and underwater tests, underground tests above magnitude 4.75 on the Richter scale, and tests in space to a distance (unspecified) at which detection was feasible. By defining the threshold in terms of seismic magnitude rather than yield, the proposal sought to avoid the problem of the substantially different coupling factors of explosions in different types of rock and in large cavities. This proposal established criteria that would have called for an estimated average of some 20 on-site inspections per year instead of the open-ended number of~the previous proposal. The United States also proposed that a joint U.S.-Soviet seis- mic research program develop techniques to Tower the threshold. In response, the Soviet Union called for a ban on all space tests, a five-year moratorium on underground tests below magnitude 4.75 while the joint seismic research program was under way, and a political decision on a specific number of on-site inspections. After meeting with British Prime Minister Harold Macmillan, Presi- dent Eisenhower agreed to the concept of a moratorium on tests below the magnitude 4.75 threshold, but only after a threshold treaty with an agreed quota of on-site inspections had been signed and a joint research program agreed upon. (The 1958-59 moratorium was no longer formally in effect, though neither side had conducted any tests since that time.) The Soviet Union accepted this approach, and arrangements were made for a Seismic Research Program Advisory Group to meet in Geneva to develop the joint program. The questions of the length of the morato- rium and the quota of on-site inspections remained. There were also unresolved political problems relating to the organization and opera- tion of the control system. Whatever prospects the threshold approach might have had ended when a U.S. U-2 reconnaissance aircraft was shot down near Sverd- lovsk on May 2, 1960. This led to a crisis in U.S.-Soviet relations and the cancellation of the Paris summit at which it had been planned to seek agreement on the duration of the moratorium and the quota of on-site inspections. The meetings in Geneva on the joint seismic research pro- gram adjourned at the end of May without filing a report when the Soviet delegation indicated there was no point in continuing. The for- mal treaty negotiations in Geneva continued but made no further pro- gress during the remaining months of the Eisenhower Administration. The Kennedy Administration The new Kennedy Administration moved promptly to revive the threshold approach that had appeared to be within reach before the U-2

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NUCLEAR TEST BANS 191 incident. On April IS, 1961, after intensive internal reviews, the United States presented a revised draft treaty banning all nuclear tests, including those in space, except for underground tests below mag- nitude 4.75. The treaty was to be coupled with a three-year moratorium on underground tests below magnitude 4.75. The moratorium could be reviewed annually while the joint seismic research program continued. Despite a number of compromises with the Soviet position, the new positions of the United States and United Kingdom and the Soviet Union were still far apart in many respects. The annual quota of on-site inspections became the symbol of these differences. The U.S.~~draft per- mitted 12 to 20 annual inspections in the Soviet Union, depending on the number of unidentified seismic events in the Soviet Union (the same formula would apply independently to events in the United States and the United Kingdom); the Soviet Union would only accept three inspec- tions. There also remained fundamental organizational differences in the two sides' approaches. For example, the United States wanted a single neutral administrator for the control system; the Soviet Union wanted a three-member administrative council (one Soviet, one West- ern, and one neutral member) that could only operate by unanimous consent. The United States wanted the detection stations in each coun- try to be manned by personnel from other countries; the Soviet Union wanted the stations to be manned almost entirely by personnel of the host country. The negotiations were stalemated, and neither side was prepared to make further significant concessions. This phase of the test ban negotiations abruptly ended on August 30, 1961, when the Soviet Union announced its intention to resume nuclear testing, which began the next day. Although there was actually no moratorium in effect at the time, the Soviet action, which came as a complete surprise, generated concern and outrage in official circles and among the public at large. When President Eisenhower had originally proclaimed a one-year moratorium in August 195S, the Soviet Union announced that it would abide by the moratorium as long as the West did. After extending the moratorium through the end of 1959, President Eisenhower, who was concerned that the United States might have to resume testing, terminated the moratorium but stated that the United States would announce any resumption in advance. When the French began testing in February 1960, the Soviet Union denounced the French action as a cover for Western testing. The Soviet Union proceeded to carry out an unprecedentedly inten- sive test series. Within 60 days the Soviet Union conducted 30 atmo- spheric tests, with greater total megatonnage than the total of all previous tests. The series included a gigantic 57-Mt test that was judged in the United States to be a reduced-yield version of the previously

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192 NUCLEAR ARMS CONTROL claimed Soviet 100-Mt bomb. As soon as Soviet testing began, President Kennedy ordered the immediate resumption of U.S. testing, and the first test was conducted within two weeks. The initial U.S. tests, which were essentially a political reaction, were conducted underground at small yield. By the spring of 1962 the United States was fully prepared and conducted Operation Dominic, a series of some 40 atmospheric tests in the Pacific that lasted over six months. Among the tests was STAR- FISH, a megaton-yield explosion at an altitude of 400 km that produced unexpected and severe high-altitude effects, including damage to satel- lites at great distances. By the end of Operation Dominic the Soviet Union was engaged in yet another major test series, including a 30-Mt explosion in early August. The cumulative effect of the massive Soviet and U.S. test series was to increase domestic and international concern about both the immediate health effects and Tonger-range military im- plications of what appeared to be a completely unbridled competition in atmospheric nuclear tests. Although the trilateral negotiations on the test ban were adjourned indefinitely in January 1962, world opinion would not permit the nego- tiations to die. Negotiations were resumed in the spring of 1962 in the Eighteen Nation Disarmament Conference (ENDC), the multilateral forum for arms control negotiations. The United States began to relax its verification demands, but this did not narrow the gap with the Soviet position because the Soviet Union hardened its position, proposing a test ban verified only by national means of detection. In the late sum- mer of 1962 the United States ant! the United Kingdom proposed two alternative approaches. One was a treaty banning all nuclear tests without a threshold on underground tests. The provisions of this com- prehensive test ban were essentially those of the previous threshold test ban, although it was suggested that the number of inspections would be reduced. The other approach was a treaty banning tests in or above the atmosphere and in the sea. The Soviet delegation rejected both ap- proaches, the first because it required inspections and the second be- cause it permitted testing to continue. In mid-October 1962 the Cuban missile crisis suddenly brought home to leaders and ordinary citizens everywhere the stark realization that nuclear war could happen. President Kennedy and his advisors were clearly deeply moved by their close involvement in the events. Secre- tary Khrushchev and his advisors also appeared to be sobered by the experience. Following the intense and continuing U.S. and Soviet atmo- spheric test series, the missile crisis intensified world pressure for pro- gress in the nuclear test negotiations, which were then the only serious, well-advanced arms control negotiations in progress. Significantly, the

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NUCLEAR TEST BANS 193 UN General Assembly passed two resolutions in the immediate after- math of the Cuban missile crisis, one calling for a cessation of nuclear testing and another calling for either a comprehensive test ban or a limited ban coupled with a moratorium on underground testing. Despite these strong pressures for an early agreement and intensive efforts over the next six months to negotiate formally at the ENDC and informally on a personal basis at various levels, the two sides were unable to resolve the remaining differences in their positions. The quota on inspections remained the major, but not the only, issue. Khrushchev reinstated his earlier offer of two or three annual inspec- tions, reportedly in the mistaken belief that this would be acceptable to the United States. Kennedy eventually agreed to reduce the quota to seven annual inspections. Neither Kennedy nor Khrushchev appar- ently considered themselves sufficiently secure politically to propose a final compromise of five inspections, which appeared to some partici- pants to be a logical outcome of the negotiating process. Kennedy was concerned over the strong opposition to further compromise from the military, the weapons laboratories, and influential members of Con- gress. Khrushchev told Western visitors that he had used up his politi- cal credit with his colleagues by agreeing to permit three inspections. The number of on-site inspections was not the only difference. There was a similar impasse over the number of unmanned automatic seismic stations, or "black boxes," to be located in each country. The United States had accepted the Soviet proposal that these black boxes, which could be safeguarded to ensure the authenticity of their seismic data, should be used in place of manned control posts to eliminate the issue of the nationality of the staff at the posts. The Soviet Union had offered to locate three black boxes in the Soviet Union, and the United States had insisted on eight to ten. The gap was not narrowed. In addition to these quantitative differences that dominated the negotiations on the test ban, the two sides were far from agreement on the so-called modalities governing the conduct of individual on-site inspections and the instalIa- tion and operation of the black boxes. Whether these detailed proce- dural issues, which were critical to the satisfactory operation of the control system whatever the quotas might be, could have been resolved if a political decision had been reached is difficult to judge. Certainly, the United States would have had to back off from the very elaborate inspection procedures it envisaged, and the Soviet Union would have had to grant considerably more access than it had yet shown signs of accepting. The treatment of peaceful nuclear explosions was an issue that had not been resolved within the U.S. government and would eventually

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194 NUCLEAR ARMS CONTROL have to be faced with the Soviet Union. Within the Atomic Energy Commission and among influential members of Congress, there was strong support for a program of peaceful nuclear explosions, called Proj- ect Plowshare, for which great economic claims were being made. But it was also recognized within the government that continuation of Project Plowshare was inherently incompatible with a comprehensive test ban. The two sides had earlier tried to finesse the issue by permitting explo- sions for peaceful purposes provided the other side could inspect the internal design of the device to assure that it was not a weapon develop- ment test. Advocates of Project Plowshare, who recognized that such a provision was tantamount to stopping the program since it was most unlikely that either sicle would agree to it in practice, proposed instead that each side be given a quota for peaceful tests or projects. Such a proposal was recognized as being inherently contradictory to the goal of a comprehensive test ban. At the urging of Prime Minister Macmillan, President Kennedy de- cided in the spring of 1963 to attempt to break out of the deadlocked ENDC negotiating framework by sending Averell Harriman to Moscow as a special personal representative to see if some resolution of the test ban issue was possible. In an exchange of personal letters, Khrushchev agreed to receive the Harriman mission. On June 10, 1963, Kennedy announced in his famous American University speech that agreement had been reached to hold high-level discussions in Moscow on the test ban. In the speech, which examined the issues of war and peace and U.S.-Soviet relations in a nuclear world, Kennedy also declared a uni- lateral moratorium on atmospheric nuclear tests for as Tong as other states did likewise. Averell Harriman's instructions were to seek a comprehensive treaty and, if this appeared unattainable, a limited agreement along the lines of the draft treaty the United States had originally submitted to the ENDC the previous year. The impasse on the comprehensive treaty and developments immediately prior to the meeting made it clear that a limited agreement was the hoped-for outcome on both sides. On July 2, Khrushchev announced that the Soviet Union was withdrawing its offer of three on-site inspections, claiming that the West would exploit them for espionage. He also stated that the Soviet Union was prepared to conclude an agreement banning testing in the atmosphere, in outer space, and underwater. The Soviet Union had previously rejected the possibility of such a limited treaty. In the United States there was growing support in Congress for this approach, which the military strongly preferred over a comprehensive test ban. The negotiations began on July 15, and ten days later the Treaty Banning Nuclear Weapons Tests in the Atmosphere, in Outer Space and

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NUCLEAR TEST BANS 195 Under Water, or simply the Limited Test Ban Treaty (Appendix D), was initiated. There was essentially no discussion of a comprehensive ban, which was clearly out of reach for quick resolution, and the negotiations proceeded directly to the text of the limited treaty. Both sides clearly wanted an agreement, and the few matters of substance and drafting problems were quickly resolved and cleared directly with President Kennecly and Secretary Khrushchev. The Soviet delegation objected to a proposed U.S. provision permitting atmospheric tests for peaceful purposes if unanimously approved. The U.S. delegation withdrew this proposal when agreement was reached on a provision permitting treaty amendment by a majority of the parties, including the three original nuclear weapon parties, and on a U.S. provision explicitly permitting withdrawal from the treaty. The Limited Test Ban Treaty, which was of unlimited duration, banned nuclear tests in all environments except for underground tests that contained the resulting radioactive debris so that it would not be present outside the territory of the country conducting the test. The treaty was to enter into force when ratified by the United States, the United Kingdom, and the Soviet Union and was open to signature by all countries. The treaty, which was considered verifiable by the National Technical Means (NTM) of the two sides, contained no special verifica- . . . talon provisions. After extensive hearings the Senate advised ratification of the treaty by a vote of 80 to 19. Support for the treaty in the hearings was not universal, with representatives of the weapons laboratories emphasiz- ing the technological limits imposed by confining testing to under- ground shots. An important factor was the support of the Joint Chiefs of Staff, whose position was uncertain until the administration formally agreed to four safeguards that the chiefs proposed. These safeguards involved presidential commitments to conduct a comprehensive and continuing underground test program, to maintain the vitality of the weapons laboratories, to maintain the resources necessary for the prompt resumption of atmospheric testing, and to improve verification capabilities. The treaty was ratified by President Kennedy on October 7, 1963., and entered into force three days later. In general, the treaty was very well received in the United States and throughout the world despite its failure to stop all testing. After the extreme tensions of the Cuban missile crisis, the first major arms con- trol agreement between the United States and the Soviet Union came as a welcome relief. The termination of atmospheric testing also relieved widespread anxiety about immediate health effects. A large number of countries moved promptly to sign the treaty, and others have joined over the years. As of September 1984, 111 countries had signed the treaty

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196 NUCLEAR ARMS CONTROL and all but 15 had ratified it. France and the People's Republic of China have not signed the treaty. Initially, both countries continued to test in the atmosphere, but since 1974 France has not conducted any atmo- spheric tests. Although the preamble to the Limited Test Ban Treaty proclaimed the objective of "the discontinuance of all test explosions of nuclear weap- ons for all times," the treaty, by stopping atmospheric testing by the United States and the Soviet Union, had the effect of reducing domestic and international pressure for a comprehensive test ban. As a result, there was little serious effort to achieve a comprehensive test ban until trilateral negotiations were resumed 14 years later in the Carter Ad- ministration. Arms control activities shifted to other fields. During the Johnson Administration the focus of arms control was on the negotiation of the Non-Proliferation Treaty (NPT) (Chapter S). The Non-Proliferation Treaty was inherently discriminatory, since it di- vided the world into nuclear weapon states and non-nuclear weapon states. To balance the commitment of the non-nuclear weapon states not to obtain nuclear weapons or any other nuclear explosive device, the nuclear weapon states agreed to share the benefits of the peaceful uses of atomic energy and to negotiate an end to the nuclear arms race. Article VT ofthe NPT specifically committed all parties to the treaty "to pursue negotiations in good faith on effective measures relating to ces- sation of the nuclear arms race at an early date." Moreover, the pream- ble to the treaty recalled the determination expressed in the preamble of the Limited Test Ban Treaty "to achieve the discontinuance of all test explosions of nuclear weapons for all time and to continue negotiations to this end." In the eyes of most non-nuclear weapon states, nuclear testing, even though it was underground, remained the symbol of a continuing policy of active discrimination uncler the Non-Proliferation Treaty. Many states considered the failure to pursue serious efforts to achieve a com- prehensive test ban to be a violation of the obligation to pursue this agreement "in good faith." This dissatisfaction continued even after the United States and the Soviet Union began the SALT process and achieved significant agreements. At the NPT review conferences in 1975 and 1980, key non-nuclear weapon states strongly criticized the United States and the Soviet Union for failing to make further progress on a comprehensive test ban. The Nixon and Ford Administrations Under President Nixon, arms control focused on the SALT process, which became the centerpiece of his foreign policy with the Soviet Un-

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NUCLEAR TEST BANS 197 ion. These negotiations produced the ABM Treaty and the SALT ~ ]:n- terim Agreement in 1972. Although both sides gave little attention initially to the nuclear test ban issue, in the second Nixon Administra- tion interest was suddenly rekindled in the threshold approach to a nuclear test ban. One must review the political situation existing at the time to appreciate this unexpected turn of events. With a summit meet- ing Tong scheduled for mid-1974, both sides shared a common interest in achieving in advance an agreement that would maintain the momen- tum of arms control and the detente process. It was clear that the SALT II Treaty, which was proving more difficult to negotiate than antici- pated, could not be completed by then. As the shadow of the Watergate scandal grew, President Nixon had an additional motivation to demon- strate that he was in control of a dynamic foreign policy. Tn these circum- stances, a threshold treaty with the threshold set sufficiently high to eliminate all verification problems and permit a significant level of testing provided an opportunity for a quick, noncontroversial agree- ment. It bypassed the problem of establishing quotas and procedures for on-site inspections and the persistent opposition of the military and the weapons laboratories to a ban on all testing. The treaty was rapidly negotiated and signed at the summit meeting in Moscow on July 3, 1974. One month later, President Nixon resigned. The Treaty on the Limitation of Underground Nuclear Weapon Tests, or more simply the Threshold Test Ban Treaty (Appendix E), prohibited any underground nuclear weapon test having a yield exceeding 150 kt. At the same time it was agreed that negotiations should continue on a comprehensive test ban. The treaty was a bilateral undertaking be- tween the United States and the Soviet Union and did not even contain provisions for other nuclear weapon states to join. The treaty included a protocol in which the parties agreed to designate the geographic bound- aries of their test areas and to exchange other technical data. These technical data, which were to be made available at the time the instru- ments of ratification were exchanged, included detailed information on the geology of the test sites and data from two calibration shots at each test site. These cooperative measures were designed to assist the other side in translating the seismic magnitude measured by its own seismic monitoring system into an equivalent yield. The seismic signal from an explosion of a given yield depends on both the local and regional geology of a nuclear test site. The two sides were concerned that tests with design yields near the threshold might accidentally produce yields above it, since the weapon laboratories wanted to test as close to the threshold as possible. To cover this contingency a separate understanding was subsequently reached that "one or two slight unintended breaches per year would not be

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NUCLEAR TEST BANS 213 heat experienced in accidents or terrorist attacks. The substitution of the new insensitive high explosives will require retesting of the im- proved weapons, since differences in the burning characteristics of these high explosives require minor modifications in design. Supporters of a CTB argue that, while improved safety is certainly desirable, the dispersal of plutonium is a relatively minor problem com- pared with the contribution a CTB would make to controlling nuclear weapons. Moreover, they observe that this problem has been recognized for some time and that any modifications that have not already been made couicl be incorporated and tested before a ban on nuclear weapon tests entered into effect. Peaceful Nuclear Explosions Some opponents of a CTB argue that such a ban would preclude the development and use of peaceful nuclear explosives, which they claim hold great economic promise. This was a major issue during the 1960s, when the U.S. weapons laboratories were widely prociair~ing the tre- mendous contributions PNEs wouIcI make in such diverse fields as gas and of] production, mining, electric power generation, and large-scale earth moving. Earth moving on a grand scale appeared the most imme- diate and dramatic application, and serious study was given to such proposals as constructing an alternate sea level canal to the Panama Canal and creating a new harbor in Australia. A major development effort, Project Plowshare, was undertaken to explore these applications. But with a more realistic assessment of the technical and political prob- lems associated with these projects as well as their economic prospects, the early enthusiasm in the United States for PNEs waned. By the 1970s the Soviet Union had become the principal advocate of PNEs. It expressed serious interest in large earth moving projects to (livers rivers so that they would flow south to the Caspian Sea instead of north into the Arctic Ocean, and a number of tests of various other applications were conducted. As a consequence of this interest, the So- viet Union, in the trilateral negotiations during the Carter Administra- tion and in its recent treaty outline, called for a ban on all military nuclear explosions but only a moratorium on PNEs until a satisfactory method could be found for preventing such activities from being used for military purposes. It is not clear whether the Soviet move was simply an effort to finesse internal pressure for PNEs or a serious effort to hold open a PNE option. Supporters of a CTB generally agree that such a treaty would prevent further progress in PNEs, since it does not appear possible as a practical

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214 NUCLEAR ARMS CONTROL matter to distinguish PNE developments from activities of potential military significance. (A few supporters of a CTB suggest that a mutu- ally satisfactory technique for continuing PNE activities might be de- veloped in the future.) All supporters of a CTB contend that PNEs are not sufficiently important to economic development to be allowed to interfere with a CTB treaty that would contribute significantly to the prospects for peace. Moreover, many supporters challenge the economic claims of PNE advocates. They also argue that many PNE applications, such as major earth moving projects, would be politically unacceptable in today's world because of the associated nuclear fallout and other effects, such as blast and earth shock. Finally, supporters of a CTB point out that efforts to accommodate a future PNE option in a CTB treaty undercut the non-proliferation value of the treaty. Some potential nuclear weapon states seized on advocacy of PNEs by the United States during the 1960s as a reason for seeking an independent capability to produce nuclear explosives. For example, the Indian government claimed that its first nuclear explosion in 1974 was actually part of a PNE program. With this history in mind, sup- porters of a CTB argue that continued efforts on the part of the nuclear powers to retain a PNE option will provide potential nuclear weapon states with a rationale for keeping open a nuclear explosives option on the grounds that it might be needed for a PNE program. The Weapons Laboratories Opponents of a CTB argue that such an agreement would seriously weaken U.S. weapons laboratories without having a comparable effect on Soviet laboratories. They assert that the agreement would deny U.S. weapons designers the opportunity to test their ideas and products. As a result, morale at the weapons laboratories would suffer, gifted weapons designers would leave, and new ones could not be recruited or trained. This would seriously impair the ability to resume vigorous weapons programs in case the agreement ended. While granting that such fac- tors would to some extent also affect Soviet laboratories, opponents assert that the Soviet Union would find ways to ensure that key person- nel remain at the weapons laboratories and continue to make signifi- cant contributions. Moreover, the potential for cheating through low-yield clandestine tests could give Soviet laboratories much greater opportunities to test new ideas and maintain a vigorous research and development program. Some opponents of a CTB argue that leaclership in nuclear weapon developments has been a major element in U.S. military strength, offsetting other Soviet military advantages, and that

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NUCLEAR TEST BANS 215 any weakening of the weapons laboratories undermines the source of this U.S. technological advantage. Supporters of a CTB argue that it is the purpose of the treaty to slow down to the extent possible all nuclear weapon developments. On bal- ance, they assert that it is not obvious that Soviet weapons laboratories would have a significant advantage in such an environment. While weapons research would clearly be curtailed, U.S. laboratories have a major advantage in their greatly superior computational equipment and their extensive experience with simulated nonnuclear effects tests. Moreover, in contrast to the Soviet laboratories, the two U.S. weapons laboratories have highly diversified research programs, with roughly one half of their present activities outside the nuclear weapons area. In addition, many of the technical and analytical problems in the peaceful inertial confinement fusion programs of the two laboratories overlap problems encountered in weapons design. Such programs should help maintain the skills of weapons designers while engaging them in inter- esting and important work. Finally, scientific productivity cannot be coerced, supporters of a CTB argue, even though the Soviet Union may be able to inhibit the departure of key scientific personnel. Verification General Verification has been a central issue in the CTB debate since the mid- 1950s. The underlying question has been, What would be the military significance of testing that could be conducted clandestinely beneath the threshold of the monitoring system? Most CTB opponents have argued that activities of military significance could be clandestinely conducted by the Soviet Union under a CTB. In contrast, most CTB supporters have argued that there would be adequate verification to ensure that the Soviet Union or other countries were not conducting nuclear tests that could have any real military significance. Nuclear explosions are unique events. The large amount of energy and forms of radiation they generate produce a variety of physical phe- nomena that can be detected at great distances. From the beginning the debate on verification focused primarily on underground tests, since tests in the atmosphere, oceans, and space appeared to be adequately verifiable. Early tests were all in the atmosphere, and by the late 1940s techniques were developed to detect even Tow-yield tests by their acous- tic signals and unique radioactive debris. Today these tests can be moni- tored very effectively from satellites through the visible and near-

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216 NUCLEAR ARMS CONTROL infrared light emitted from the explosion. Underwater nuclear ex- plosions can be monitored to very Tow yields, far below the threshold of underground tests, by existing acoustic sensors associated with anti- submarine warfare systems. Nuclear explosions in space at vast dis- tances can be monitored from satellites by their characteristic X-ray . . emissions. Underground tests present a more serious technical challenge. The seismic signals they produce must be not only detected but distin- guished from a large background of seismic signals from natural earth- quakes whose numbers rapidly increase at lower magnitudes. The identification process benefits from the fact that the seismic signals of explosions differ in a number of significant ways from those of earth- quakes. Explosions are a point source of energy in space and time, while earthquakes result from the slipping of faults over a considerable dis- tance. Over the last 25 years there has been a major effort to understand this problem and to improve the capabilities to monitor underground tests. A number of seismic techniques that were available from the begin- ning of the debate have been refined. These include seismic determina- tion of the location and depth of the event and the "first motion" of the initial compression wave transmitted through the earth. Over the years a number of additional techniques have been developed that depend on the differing spectrums of the seismic signals from explosions and earthquakes. Specific criteria are sometimes difficult to formulate, but many seismologists believe that the overall spectrum and complexity of seismic signals clearly differentiate the two types of events. Experts, including those opposed to a test ban, generally agree that these collective criteria can separate explosions from earthquakes and identify suspicious events, but assessments of the threshold of identifi- cation and level of confidence differ. Location can normally be deter- mined with confidence to within 25 km. Depths can be determined to within 15 km, which is greater than current drilling capabilities. Most earthquakes (more than 90 percent) are either located in the deep ocean or more than 30 km underground, which automatically eliminates them from concern. Of the earthquakes in the Soviet Union and its coastal waters, 75 percent are in or near the Kamchatka Peninsula and the Kurile Islands and tend to have very deep focuses and to be offshore. With these events eliminated, an estimated average of around 100 earthquakes per year occur in the Soviet Union with body wave magni- tudes greater than 3.S on the Richter scale (equivalent to less than a 1-kt explosion in hard rock). Originally it was proposed to identify these residual earthquakes by

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NUCLEAR TEST BANS 217 the so-called first-motion criteria. An explosion sends an initial com- pression wave through the earth in all directions, since it compresses the surrounding medium symmetrically. An earthquake, which is gen- erated by a sTipfault, sends initial compression waves in some directions and rarefactions in others. This provides a very powerful technique for differentiation provided there are enough stations in the monitoring system and the signal is sufficiently strong to be recorded with confidence. The discriminants that compare various segments ofthe seismic spec- trum take advantage of the fact that earthquakes put a substantially larger fraction of their energy into modes other than compression waves because of the complex nature of their sources. In exploiting this well- established phenomenon, particular attention has been given to com- paring the magnitudes of a given event as measured by surface waves and by body waves. An explosion with the same body wave magnitude as an earthquake has a much smaller surface wave magnitude, since much less of its energy goes into surface waves. This same general phenomenon leads to a number of more qualitative criteria that are very persuasive to most seismologists. The coupling of energy from a nuclear explosion to its surroundings creates another problem. The seismic monitoring system measures the seismic magnitude, not the yield, of an explosion. The yield equivalent to a seismic signal must be estimated by calibration shots or caTcula- tions. The coupling factor depends not only on the immediate medium in which the explosion occurs but also on the general geologic location of the event. In general, equivalent yields are referred to hard rock, which gives the best coupling of energy between an explosion and the sur- rounding medium. The poorest coupling occurs in deep dry alluvium deposits, which may have a coupling factor only one-tenth that of hard rock. If a nuclear test occurs in a sufficiently large cavity that does not collapse during the explosion, it is theoretically possible to reduce the coupling by a factor of as much as 100. In addition, there are regional biases in the coupling of seismic signals. For example, most seismolo- gists believe that seismic body waves from the shots at the U.S. test site in Nevada, where the United States obtains its calibration data to re- late magnitude and yield, are by virtue of the regional geology less well coupled than are Soviet explosions in the Semipalatinsk test area. If correct, this would cause a systematic overestimation of the test yields at Semipalatinsk. However, in the absence of reliable calibration data, the precise magnitude of such an effect remains uncertain. By visiting the site of a suspicious seismic event, it is possible to obtain direct or indirect physical evidence of a nuclear explosion. From

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218 NUCLEAR ARMS CONTROL seismic data alone the location of the event is uncertain to within 10 to 25 km. However, information from other National Technical Means may focus attention on a specific location because of surface collapse, scarring, or evidence of unusual human activity. On the ground, investi- gators might find telltale traces of escaping radioactive gases or circum- stantial evidence of surface fracturing or human activity that would lead to further efforts to obtain definitive samples of radioactive debris. Threshold of Detection and Identification Opponents of a CTB argue that tests with significant yields could be tested under that threshold of identification or even the threshold of detection. Even without sophisticated evasion techniques, according to some opponents, the Soviet Union could be confident of successfully conducting explosions with yields in the 10- to 20-kt range by testing in dry alluvium, a light sandy material. They point out that thresholds of a kiloton or so assume hard rock coupling. Some opponents also argue that by firing shots in large underground cavities, the Soviet Union could clandestinely conduct tests with yields up to 100 kt. Supporters of a CTB argue that the system that the Soviet Union appeared to be prepared to accept would have an effective threshold of identification of around 1 kt. They assert that in hard rock the threshold would actually be less than 1 kt. While agreeing that equivalent yields would be greater in other media, they assert that the extreme case of dry alluvium is misreading since this material does not exist in the Soviet Union at depths necessary for clandestine testing above a kiloton. Moreover, they point out that even when fully contained, shots in allu- vium and other media that couple less well than hard rock at the Ne- vada test site leave distinctive subsidence craters that can easily be identified from the air. By properly distributing 10 or 15 unmanned seismic stations within the Soviet Union, according to supporters, the threshold of identification for explosions in any medium, including allu- vium, would be a kiloton or less. Supporters of a CTB argue that the threat of evasion posed by "big hole" decoupling has been greatly exaggerated by opponents of a CTB treaty. They point out that the cavity required to decouple a 100-kt shot would have to be 150 m in diameter at a depth 2 km below the surface, an unprecedented engineering project in hard rock. A more practical approach would be to create a cavity in a salt dome by solution mining, although such cavities would be restricted to much smaller sizes. How- ever, these supporters assert that the only suitable salt domes in the Soviet Union are located in the Caspian Sea area and could be specially monitored by a few properly located unmanned seismic stations. These

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NUCLEAR TEST BANS 219 stations, which because of their location could record close-in seismic signals, would be extremely effective since any seismic disturbance in this aseismic area would be a suspicious event. With such a monitoring system, some of these supporters argue, clandestine tests could not as a practical matter be successfully concealed in these salt domes at yields much above a kiloton. Hiding in Earthquakes Some opponents of a CTB contend that it would be possible to test clandestinely by carrying out the test during a major earthquake so that the seismic signal from the explosion would be lost in the earth- quake's extended seismic disturbance. They assert that it would be possible to design a test so that a device with a yield far above the threshold of the monitoring system could be held in readiness for an extended period and fired at the proper moment to avoid separate detection. Supporters of a CTB dismiss this as a serious clandestine testing technique. A test program conducted by holding devices in readiness for months or years to be fired on one or two minutes notice after the initial detection of an entirely unpredictable event is not credible, they main- tain. Moreover, in the very unlikely event that such a clandestine test were attempted, it would be extremely difficult to hide from the pro- posed monitoring system if it were significantly above the threshold. Supporters point out that it would be virtually impossible for the Soviet Union to conduct such a test near the origin of a large earthquake. The only area of the Soviet Union that has such earthquakes with reason- able frequency is the Kamchatka Peninsula and Kurile Islands region, where seismic events can be carefully monitored by nearby seismic equipment in Japan and Alaska, by very sensitive underwater seismic arrays, and by any unmanned seismic stations located in the immediate area as part ofthe monitoring system in the Soviet Union. Since the test would have to be hidden in the signal from a distant earthquake, it would be very difficult to match the exact timing and magnitude of the test with the arriving earthquake signal. Even if this extremely diffi- cult task were successfully accomplished, supporters assert, there is a good chance that the test would still be identified as a separate, and therefore very suspicious, event. Nonseismic Information Some opponents of a CTB argue that nonseismic sources of informa- tion cannot be counted on to help verify compliance. They point out that

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220 NUCLEAR ARMS CONTROL if the Soviet Union attempted to evade the agreement, it would be extremely careful to avoid obvious activities that might arouse suspi- cion in advance or help identify a test after the fact. Supporters of a CTB argue that nonseismic sources of information would contribute significantly to verification capabilities. Satellite photography would contribute in many ways to determining whether an unidentified seismic event was in an area of other suspicious act~vi- ties. Such reconnaissance could narrow, or even pinpoint, areas of con- cern for an on-site inspection. For example, efforts to construct a big hole for decoupling purposes or the subsidence crater from a shot in alluvium or other media would be easily identified by such observa- tions. These supporters emphasize that the deterrent value of the entire intelligence operation should not be underestimated since the Soviet Union could not be certain that information suggesting the evasion of a test ban would not come to the attention of U.S. or allied intelligence from technical or human sources. On-Site Inspection Opponents of a CTB tend to argue that the right to a substantial number of on-site inspections is essential to a verifiable agreement. Some opponents take the position that this is the only way to prove a violation. Others assert that individual on-site inspections would be so ineffective that even substantial numbers would have little chance of discovering a clandestine test program. The seismic monitoring system would only locate an event to within 10 to 25 km, they point out, and a deeply buried shot would produce little, if any, surface disturbance. Opponents argue that on-site inspections must be mandatory to b useful. Invitational inspections of the type envisaged in the trilateral negotiations during the Carter Administration would be of little or no value, they assert. It is unrealistic to imagine that a country would invite an inspection if there had actually been a test unless it was certain that the test could not be discovered. Supporters of a CTB argue that on-site inspections, even if they re- quire an invitation after a challenge, are a useful deterrent to ciandes- tine testing. However, they disagree that an on-site inspection is needed to make the case that a nuclear test has in fact occurred since seismic criteria are capable of identifying most explosions as explosions above the threshold with high confidence. White agreeing that an invitation would be unlikely in the case of an actual test, these supporters argue that if serious suspicions existed, the denial of an invitation without a very persuasive explanation would indicate that a violation had in fact

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NUCLEAR TEST BANS 221 occurred. Consequently, there would be a strong motivation to grant an invitational inspection to clear the record if, in fact, there had not been a clandestine test. Supporters contend that individual inspections could be very effective in resolving specific suspicious events. While seismic means alone could only locate the event to within 10 to 25 km, satellite reconnaissance could identify surface subsidence or suspicious human activities that couIc3 focus the inspection process. During the inspection, the presence or absence of traces of unique radioactive gas and of characteristic surface disturbances could adequately resolve suspicious cases. Significance of Testing Below the Threshold Opponents of a CTB argue that even below a kiloton the threshold claimed by many CTB supporters important weapons work could still continue on tactical weapons, weapons effects, and the physics of weap- ons design. They also contend that at a threshold of 10 to 20 kt, which many opponents believe is a more realistic estimate, it would also be possible to carry out some important reliability tests that could help maintain confidence in the stockpile. Opponents would also argue that if the threshold can be pushed up to 25 to 100 kt with big hole decoupling or by hiding tests in earthquakes, it would be possible to make major developments in certain types of nuclear weapons and test the reliabil- ity of any nuclear weapon regardless of its design yield. In this connec- tion, some opponents would note that, while a major development program would require many tests, only a few tests would be required to maintain confidence in stockpile reliability. Opponents also emphasize the importance of any of these test programs to sustaining the effective- ness and responsiveness of Soviet weapons laboratories. In this way, the Soviet Union could have an option to resume testing openly with an asymmetric advantage. Supporters of a CTB argue that clandestine testing below a kiloton or even several kilotons would not contribute to existing Soviet weapons capabilities. It would also not give the Soviet Union an asymmetric advantage in reliability testing, they continue, since the operation of most warheads, including all of those on strategic systems, could not be confirmed at these low yields. Moreover, supporters question whether such testing would give the Soviet laboratories any real advantage in maintaining interest and morale, since U.S. laboratories would have opportunities to continue work with computers and simulated nonnu- clear effects and to carry out related peaceful research activities. Sup- porters dismiss as unrealistic the possibility that testing at yields much

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222 NUCLEAR ARMS CONTROL above a few kilotons could be carried out and note that many tests would be required to conduct a sustained weapons development program. Con- sequently, these supporters conclude that a clandestine program would not have any effect on the military balance. Significance of Very Low Yield Tests Some opponents of a CTB argue that nuclear tests of military interest can be conducted at such low yields, a few tons or less, that there is no possibili by of detection. They assert that these experiments, which can be condo Acted at a laboratory, are useful in studying the physics of nu- clear em '1osions, in advancing safety, and in maintaining laboratory competence and interest. They also point out that, if taken literally, a complete ban on all nuclear explosions would also ban the peaceful inertial confinement fusion program, which involves a continuous pro- cess of tiny explosions and possibly other approaches to controlled ther- monuclear power as well. It is a fundamental error, they contend, to include in a ban a category of activities that is clearly unverifiable. Supporters of a CTB argue that this is not a real problem affecting U.S. security interests since these tests would not significantly advance either side's nuclear weapons program. The problem can be handled either by a formal definition of nuclear explosions at a very Tow level or by an unstated de minimis interpretation that would effectively ex- clude very Tow level laboratory activities from the ban. Supporters add that the history ofthe CTB negotiations makes it clear that neither side had any intention of banning the inertial confinement fusion program or other efforts to develop fusion or fission reactors. Impact on Nuclear Proliferation Opponents of a CTB argue that it would not be an important factor in non-proliferation. The potential nuclear weapon states of real concern would not sign such a treaty, they assert, since these states wish to maintain a nuclear weapons option. These countries have their own security concerns that have little or nothing to do with whether the United States and Soviet Union are continuing to improve their nuclear weapons. The pressure to join a CTB is further reduced by the fact that France and China most likely will not join such a treaty in the foresee- able future. Opponents also argue that potential nuclear weapon states will be able to develop a nuclear weapons option and even stockpile simple nuclear weapons without testing. In support of this contention, they

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NUCLEAR TEST BANS 223 point out that Israel has apparently been able to develop a first genera- tion nuclear weapon without a test. Other countries may follow this example even if they join a CTB or are indirectly constrained by it from testing. Supporters of a CTB argue that it would be a key factor in creating a nuclear regime conducive to non-proliferation. Many non-nuclear weapon states have consistently and bitterly complained about the dis- criminatory nature of the present international nuclear regime. These states particularly object to the continuation of nuclear testing, which they see as a symbol both of the threat of nuclear war and of the inequi- table nature of the Non-Proliferation Treaty. Supporters argue that a CTB treaty would go a Tong way in the eyes of the non-nuclear weapon states to meeting the obligation that the United States and the Soviet Union undertook in Article VT of the NPT "to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date." Many potential nuclear weapon states would sign a CTB treaty, ac- cording to supporters. Even those that chose not to sign would be uncler greatly increased international, and in some cases domestic, pressure not to undertake nuclear testing. Thus France, a nonsignatory to the Limited Test Ban Treaty, discontinued atmospheric testing in 1974. Despite the apparent example of Israel, these supporters contend that it would be much more difficult technically and politically for most coun- tries to develop a nuclear weapons capability without testing. This would be particularly true in countries without the technical expertise of Israel or in which the military did not have confidence in a relatively inexperienced scientific community. In any event, it would be ex- tremely difficult for present non-nuclear weapon states to go beyond relatively primitive first generation nuclear fission weapons without testing, and it would be impossible for them to develop thermonuclear weapons.