at declared facilities-in this case the site of nuclear tests. Joint Soviet-U.S. discussions to establish direct yield measurements will necessarily require negotiation of all the logistical aspects of such onsite presence, including the size and composition of the technical teams who would make measurements; agreement on the quantity of equipment which can be brought into the country; identification of allowed instrumentation; inspection of equipment by the party whose test is to be measured; establishment of housing, feeding, and transportation arrangements for the team making measurements; and procedures for sharing and transferring data from the country in which the test is to be performed. Though not exhaustive, the above issues that would require negotiation are indicative of the long list of issues which must be addressed in making the transition from an agreement in principle to onsite inspection implementation. Any one of these elements, if not properly resolved, could frustrate the ultimate objective of the inspection regime. While not as glamorous as some aspects of arms control, the negotiation of such technical and logistical details is critical and may be extremely time consuming. Therefore, early joint Soviet-U.S. discussion of these issues can have a major impact on timely ratification of the TTBT and PNET. b. Detection and Identification of Low-Yield Nuclear Tests. The second problem area, detection and identification of low-yield nuclear tests, is even more difficult because the solution requires effective monitoring in all environments-underground, underwater, in the atmosphere, and in outer space. Consequently, verification of any limitation of low-yield nuclear tests would require, at a minimum, the utilization of several techniques. For example, detection and identification of low-yield nuclear tests will necessitate installation of an in-country seismic network and the implementation of onsite inspections. In addition, regional seismology (operating distances up to 2,000 kilometers from the source) will be a critical technology for the detection of underground tests. Measurement techniques for the collection and detection of atmospheric nuclear explosion debris will still require some refinement when working at or near levels of naturally occurring background radiation. Further development of hydroacoustic techniques could contribute to detection of small nuclear tests in remote ocean areas. Recognizing the full scope of the problem of detecting and identifying lowyield nuclear tests in all environments, which must be solved, this paper will address only one part of the problem-monitoring low-yield underground nuclear tests--because this is the area where the United States believes that cooperation with the U.S.S.R. would be the most productive. The requirements for in-country monitoring stations have been discussed with the Soviets in many fora since the late 1950s (see the "Historical Perspective" section.") There remain several areas in which seismic monitoring can be profitably addressed by Soviet and U.S. technical experts. Further work may strengthen the basis for seismic detection and identification of low-yield nuclear tests in advance of the achievement of the other criteria which must be met before "Not printed here. the United States could consider a comprehensive test ban to be in its national interest. It is assumed that whatever the level of detection of seismic events, there will be some events detected whose origin (e.g., nuclear tests, earthquake, chemical explosion) will be uncertain-unidentified (i.e., unresolved as to their origin) events. While improvements in seismic monitoring devices could be expected to provide additional data that could identify some of the events that cannot be identified at current sensitivity levels, the net effect of improvements in sensitivity will be to increase the number of unidentified events. Onsite inspection, as a concept, is also used to describe inspections conducted to remove ambiguity when information from other sources indicates that a potential violation of a treaty in force may have already occurred. However, onsite inspection will only be useful when the precise location of the ambiguous event can be determined. Onsite inspection could contribute to identification of the source of surface or near-surface explosions, where surface disturbances would clearly indicate the location. For small underground explosions, it would be nearly impossible to locate the source with sufficient precision to permit the verifying party to drill into the cavity created by the test to sample the explosion debris. The basic elements which could be addressed in joint discussions include the fundamental science of the transmission of seismic waves within the Soviet Union; the types of equipment which would need to be permanently installed for the measurement of seismic data; the equipment which would need to be installed for the recording and transmission of seismic data to national data analysis centers; and the numerical data-processing techniques which would be used for identifying the source of a seismic event based on the characteristics of the seismic data. These issues are described in more detail below: • Seismic Wave Transmission: The United States is actively pursuing the seismic research which would be critical to the detection and identification of low-yield (below 10 kt) nuclear tests. Of particular significance is research on high-frequency seismic waves. Instruments capable of detecting high-frequency seismic waves have been developed and an experimental seismic array containing such equipment is in operation. To be confident that high-frequency seismic waves can be useful for detection and identification of low-yield nuclear tests, two issues need further study: the availability of sufficiently quiet, low background seismic noise sites within the Soviet Union at which seismic stations could be located and knowledge of the transmission characteristics of highfrequency seismic waves within the Soviet Union. The degree to which seismic wave energy is absorbed and scattered as a seismic wave travels away from a nuclear explosion in the United States has been studied extensively, and much of this work has been published in the scientific literature. Similar information is not available for explosions within the Soviet Union. A joint U.S.-Soviet effort could seek to determine the degree to which high-frequency seismic wave energy is absorbed and scattered in the Soviet Union. Such an effort would establish a more realistic basis for the utility of highfrequency seismic waves for detection and identification of low-yield nuclear tests. While data obtained from outside the Soviet Union are useful, Soviet-U.S. cooperation in obtaining and evaluating data from within the Soviet Union is essential. • Seismic Equipment and Data Handling: During the trilateral CTB negotiations of 1977-80, the United States described to the Soviet Union tamper-proof, remotely operated seismic stations which would record and transmit seismic data for analysis in the United States. The United States has continued research on such stations. Modification in these stations would be required to provide the capability to record and transmit data on high-frequency seismic waves. Joint Soviet-U.S. efforts could resume on the criteria for the location and operation of such stations to include characterization of the sites which would have to be available to ensure accurate instrument operation. Such an effort would have to include data gathering from potential sites for remote stations in the Soviet Union and should include installation of research instruments to validate that such instruments can operate reliably, to include data transmission, throughout the broad range of environmental conditions within the Soviet Union. • Seismic Wave Analysis: The effectiveness of any low-yield underground nuclear test verification regime based upon the analysis of seismic waves will ultimately depend on the ability to identify a nuclear explosion by distinguishing between nuclear explosions and other sources of seismic energy, e.g., chemical explosions and earthquakes. The object must be to minimize the number of recorded seismic events whose source is ambiguous. A joint Soviet-U.S. effort could seek to identify analytic techniques which would positively identify the origin of recorded seismic signals. Such a joint study cannot be done in the abstract but should be tested against real data which would be typical of that which would be recorded by instruments located at the prospective location of seismic stations. No analytic technique can hope to eliminate all ambiguous events, but it would be very helpful if the two sides could agree on which technique can be the most effective. V. Current Status We have sought on a number of occasions in the past several years to engage the U.S.S.R. in discussions on verification improvements in the nuclear testing area but thus far without success. In 1983 the U.S. Government sought on three separate occasions to engage the Soviet Union in a discussion of essential verification improvements for the TTBT and the PNET. In September 1984 the President proposed in his address to the UN General Assembly that the United States and the Soviet Union find a way for Soviet experts to come to the U.S. nuclear test site and for U.S. experts to go to theirs to measure directly the yields of nuclear weapons tests. In July 1985 the President expanded his offer with an unconditional invitation for Soviet experts to go to the U.S. nuclear test site to measure the yield of a U.S. nuclear test with any instrumentation devices they deemed necessary. There was no requirement for a reciprocal visit by U.S. experts to a Soviet test site. In December 1985 President Reagan proposed to Documents on Disarmament, 1984, p. 692. 8 Ibid., 1985, pp. 443-444. General Secretary Gorbachev that U.S. and Soviet experts on nuclear testing limitations meet in February 1986 to discuss our respective verification approaches and to address initial tangible steps to resolve this issue.? Most recently, on March 15 [14], 1986, the President urged the Soviet Union to join the United States in discussion on finding ways to reach agreement on essential verification improvement of the TTBT and PNET.10 In this respect he provided details to the Soviet Union on the U.S. CORRTEX hydrodynamic measurement system and proposed that General Secretary Gorbachev send Soviet scientists to our Nevada test site during the third week of April 1986 to fully examine CORRTEX. At that time, the Soviets could also monitor a U.S. nuclear test. Finally, the President indicated that, if the Soviet Union will join us in an agreement for effective verification, including the use of CORRTEX, the United States would be prepared to move forward on ratification of the TTBT. The Soviets have stated that they have developed and have available a system that is used to obtain data similar to that obtained by CORRTEX. Aside from this assertion, the Soviet Union has not responded to any of the above U.S. initiatives, which were aimed at constructively addressing our mutual concerns." 150. Letter to the Editor of The New York Times From the Legal Adviser of the Department of State (Sofaer): Negotiating Record of the Anti-Ballistic Missile Treaty, August 15, 19861 To set the record straight, your readers should know that, contrary to Senator Sam Nunn's comments quoted by Anthony Lewis (column, Aug. 4), I have always favored Senate access to the entire, relevant antiballistic missile treaty negotiating record. The Administration and the Senate worked out a proper format for that access after Senators Richard Lugar and Claiborne Pell sought it in a manner to which the Administration was able to respond positively. The W.C. Fields aspect of this affair is not, as Mr. Lewis contends, the Administration's position, but the fantasy of some people that we have something to hide. The record will show that our ABM treaty negotiators failed to obtain the definitive language they were instructed to present, or any adequate substitute, because of firm Soviet opposition to regulating substitute “devices" for ABM components. 9 Ibid., pp. 930-931. 10 Document 35. "For the TASS statement on the proposal, see Document 36. 'The New York Times, August 19, 1986. Copyright © 1986 by The New York Times Company. Reprinted by permission. 2 For the text of the Treaty, see Documents on Disarmament, 1972, pp. 197–201. 151. Soviet Paper Submitted to the Conference on Disarmament: Verification of a Nuclear Test Ban, August 15, 19861 (Proposal concerning the exchange of Level II seismic data) The cessation and prohibition of nuclear testing is a paramount disarmament issue, the radical resolution of which would put an end to the qualitative improvement of nuclear weapons and development of new models and types of such weapons, and at the same time could mark a turning point in the efforts to avert the nuclear danger. The cessation and prohibition of nuclear tests must be reliably verified. The Soviet Union is in favour of the use for such purposes of every possible form of control, both national and international, including on-site inspection and the installation of devices. The international exchange of seismic data must play an important part in the arrangements for international verification that nuclear tests are not being carried out. Currently, the possibilities of seismic verification of the non-conducting of underground nuclear explosions have increased considerably in line with the intensive development of the means for digital recording, transmission and processing of seismic data. Advances in recording devices and methods of data analysis now allow a wider use of signal records themselves, in other words, of Level II seismic data. Modern methods of analysis, at stations, of seismic wave forms in digital form, as well as frequency and polarization filtering, make it possible to extract signals from weak explosions given signal-to-noise ratios in the order of unity, and consequently to improve the threshold possibilities of the stations in the global network. The use of Level II data at international centres in the preparation of seismic event bulletins will make it possible more accurately to diagnose the nature of seismic events, assess the source parameters as well as its power, epicentre co-ordinates, and event onset time and, especially, depth. In addition, the use of the signal records themselves at international centres will reduce the number of unassociated signals of both body waves and surface waves. All of this ultimately leads to a considerable enhancement of the effectiveness of the international system for the exchange of seismic data. The Ad Hoc Group of Scientific Experts to Consider Co-operative Measures to Detect and Identify Seismic Events is making a useful contribution to working out methods of seismic verification. Since it is important, for the purposes of effectively verifying that tests are not carried out, that use should be made of all advances in seismology, it is essential that the Group should pursue its work. In the view of the Soviet Union, the Ad Hoc Group should set about devising a system for the prompt transmission of Level II seismic data, which would underpin the international seismic verification of the non-conducting of nuclearweapon tests. Such data would be transmitted promptly from the seismic stations belonging to the global network using satellite communication channels, and 'CD/724. |