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Disarmament Diplomacy

Issue No. 51, October 2000

Verifiability of the CTBT: The Report of the Independent Commission

By Trevor Findlay


The Independent Commission on the Verifiability of the Comprehensive Nuclear Test Ban Treaty (CTBT), meeting in London on October 26 and 27, agreed a consensus report which concluded that the treaty is verifiable with ' probability' Although the CTBT, opened for signature in 1996, has not yet entered into force, its verification system is progressively being assembled under the auspices of the treaty' Preparatory Commission (PrepCom) in Vienna. Taking into account both the system mandated by the treaty and additional verification means available to the international community, the Commission drew attention to the complex and constantly changing verification gauntlet that any potential violator would have to confront. These global verification capabilities, according to the Commission, together will constitute a powerful deterrent to any state contemplating an illicit nuclear test. This paper looks at the work of the Commission, and assesses its potential contribution in maintaining and bolstering confidence in the evolving regime.

Origins of the Commission

The Independent Commission was established by VERTIC, the Verification Research, Training and Information Centre, a London-based non-governmental organization.1 The idea for the Commission arose in response to the decision of the US Senate in September 1999 to vote against recommending US ratification of the treaty. This outcome was partly due to controversy over verifiability. Most observers had presumed that this issue had, in broad terms, been laid to rest when the US had agreed to the commencement of CTBT negotiations in the Conference on Disarmament in 1993, and when it had subsequently concurred in the agreed treaty text and signed it in 1996. Many observers, including VERTIC, felt exasperated by how little time had been allowed for during the Senate debate for consideration of the complexities of verification and by the number of false or misleading allegations about verifiability that had gone unchallenged. In particular, just days before the vote, press reports appeared, based on leaked intelligence information, claiming that Russia had conducted small nuclear tests undetected by the international community.

As an organization founded in 1986 to deal with the very issue of verifiability of a then future test ban treaty, and which had paid close attention to CTBT verification ever since, VERTIC seemed well placed to initiate an independent study of the issues raised in the foreshortened US debate. A second consideration in VERTIC' decision to establish the Commission was its awareness that in 1999 the CTBT Organization (CTBTO) PrepCom had marked the third anniversary of the commencement of its work in setting up the treaty' verification system. It seemed a timely juncture to consider how far they had progressed and what remained to be done.

The Commission

The Commission comprised 14 scientists and experts from 11 different countries who were selected for their expertise in one or more of the verification technologies or techniques requiring consideration (see list of Commissioners below). Commissioners were drawn from the future CTBTO' Provisional Technical Secretariat, government agencies and academia and non-governmental organizations. The Japanese Ambassador to the UN in Vienna, Nobuyasu Abe, was included for his involvement in efforts by the CTBT' signatory states to ensure that the treaty enters into force as soon as possible (the so-called Article XIV process). Also among the Commissioners was an eminent scientist proposed by the UK' Royal Society, Professor Herbert Huppert of Cambridge University, whose role was to audit the proceedings from the perspective of someone outside the verification community. Commissioners were asked to act in their own personal capacities and not to represent their organization or country.

Regrettably, VERTIC was only able to recruit one woman to the Commission - Dr. Elisabeth Blanc from France - and no developing country representatives; this partly reflects the current uneven societal and global spread of CTBT-relevant verification expertise.

The Mandate

The Commission was tasked with assessing the verifiability of the CTBT both now, when the treaty' verification system is still being assembled, and in the future, once the system is complete. The Commission was also enjoined to consider the totality of the verification resources available worldwide, whether inside or outside the treaty regime, and the likelihood of synergies between the various types of data whatever their origin. The particular topics Commissioners were asked to study were:

  • the current and planned verification capabilities of the International Monitoring System (IMS) and International Data Centre (IDC) being established by the CTBTO PrepCom;
  • the current and future capabilities of the four monitoring technologies which will be part of the IMS (seismic, radionuclide, hydroacoustic and infrasound) and the possible synergies between them;
  • the preparations for and likely capabilities of the On-Site Inspection (OSI) arrangements for the CTBT;
  • the contribution of National Technical Means (NTM), including remote sensing from space, to CTBT verifiability;
  • the potential contribution to verifiability by non-governmental organizations and scientific networks outside the official verification system;
  • possible evasion scenarios and responses;
  • the issue of sub-critical testing and verification; and
  • confidence-building and other co-operative measures to enhance verification.
The aim was to produce a brief, 8-page report, which, while scientifically rigorous, would be accessible to policymakers who need to make decisions about whether or not their country should sign and/or ratify the CTBT. The report would be accompanied by an annex which would contain scientific papers contributed by each of the Commissioners, in which their technical arguments could be elucidated.

The Commission was assembled and commenced work in August. Between then and October the Commission began drafting its report '', via e-mail, producing several iterations. At their first and only face-to-face meeting in London in late October, the Commissioners adopted their Final Report by consensus. The telescoped timetable was necessitated by the fact that elections in the US in early November would produce a new President, Administration and Congress, providing an opportunity for new thinking to have an impact. Moreover, there would be several other reports emerging on the CTBT issue, including one by the official CTBT Task Force appointed by President Clinton and headed by General John Shalikashvili. It was hoped that the Independent Commission' report, which restricts itself to the verifiability question, would be able to have an impact on these wider-ranging studies.

The Report

The Commission' report is a carefully balanced assessment of the verifiability of the CTBT. It does not claim that the treaty is 100% verifiable, but it does make a strong case that there is a high probability that any event that might give rise to concern - as being a possible clandestine nuclear test - will be detected, located and identified.

The Commission, rightly, was unwilling to attach a precise percentage figure to the probability that this could be achieved by the International Monitoring System, either in terms of the system as a whole, or in respect of the four different technologies involved. Nonetheless, it expressed confidence that explosions as low as 1 kiloton (and in some cases much lower) in all environments would be detected with a high degree of confidence - and hence deterrence. Commissioners noted that even the partially completed IMS already has capabilities below 1 kiloton in some regions, particularly Central Eurasia.

The report highlighted the impressive capabilities of two often overlooked IMS technologies - hydroacoustic and infrasound - used to detect explosions, respectively, under the sea and in the atmosphere. They may also help detect underground nuclear tests, complementing data from the ubiquitous seismic network. The report notes the synergies both among these three ' form' technologies and between them and the radionuclide network, which will detect radioactive debris and gases from nuclear tests. In addition to detection, the location and identification of nuclear tests would likely involve using data from one or more of the four IMS technologies, again exploiting their synergies.

Radionuclide detection technology was in fact described as providing the ' gun' for verifying non-compliance with the CTBT, particularly when obtained during an on-site inspection (OSI). This is because it could definitively distinguish a nuclear explosion from a conventional explosion in a way that the wave form technologies cannot. The Commissioners noted that a well-prepared OSI regime should serve as a deterrent, discouraging any potential violator because of the high probability of exposure.

The Commission' report describes the progress made to date in establishing the elements of the International Monitoring System, noting in particular that key components of the system' Global Communications Infrastructure are in place and that the International Data Centre has already demonstrated that it can receive and process data and distribute it in a timely manner to states parties.

One of the innovations of the report is its holistic approach to CTBT verification, something that was not evident during the US Senate debate, where the focus was on the alleged shortcomings of the IMS. Commissioners became acutely conscious during their deliberations that, in addition to the IMS and the other components of the treaty regime, there are considerable additional verification resources on which the international community can draw to provide reassurance that the CTBT is being complied with. The treaty itself provides for information from national technical means of verification - information-gathering capabilities owned and operated by governments - to be used by a treaty party in seeking clarification and consultation with regard to a suspicious event, or as the basis of a request for an on-site inspection of another state party.2 In addition, of course, NTM are used by states unilaterally to reassure themselves that their fellow treaty parties and other states are not conducting nuclear tests.

While the report notes that some NTM capabilities are classified, it also points out that there are now thousands of openly accessible scientific and environmental monitoring resources that may provide evidence of a clandestine nuclear explosion. These include increasingly available and cheap commercial satellite imagery and a global scientific seismic network. In the coming decade the scientific network is likely to include thousands of digital seismic stations worldwide which will be recording earth movements, including illicit nuclear tests should any occur. Information derived from these sources, too, could be used synergistically with data from the IMS.

The Commission spent some time considering the likelihood that a country would attempt to cheat the verification system through some elaborate evasion scenario. Three were considered: decoupling, hiding a nuclear explosion in another event, and conducting an explosion in an area and in an environment where attribution could be problematic. The latter two scenarios were dismissed on the grounds that no credible examples of how they might work could be identified. The most discussed option was so-called decoupling, in which an attempt is made to attenuate the seismic signals of an underground nuclear explosion by detonating it in an underground cavity, either an existing one or one constructed for the purpose. Commissioners agreed that such an undertaking faced many technical, financial and organizational hurdles and would expose the perpetrator to a complicated verification gauntlet. They concluded that even sophisticated nuclear-weapon states would have difficulty in executing such a scenario because of the complexities involved, not least ensuring secrecy and a foolproof means of hoaxing all elements of the verification regime.

The report ends by recommending that states provide the necessary political, financial and technical support to permit the CTBT regime to be established as soon as possible, that the international community support greater exchange of data for between the IMS and non-IMS sources, and that research into the scientific and technical underpinnings of CTBT verification be nourished.


The report is a sober, balanced, independent assessment of the verifiability of the CTBT. A group of scientists and experts from a wide variety of fields and backgrounds were obliged to not only assess the capabilities of their own verification specialities but those of others. Those Commissioners with backgrounds in the official treaty system and within governments were required to consider the contribution that additional verification means could make to the international community' assessment of verifiability. In turn, those from outside the system were forced to make a considered judgement of the value of the treaty' own dedicated verification means. To this extent the Commission contained within it checks and balances that lend credibility to its findings.

While acknowledging how much work remains to be done on the IMS, the Commission' report reveals the surprisingly good capabilities of a system that is still being established. But the most telling feature of the report, and perhaps its unique contribution, is its holistic, inclusive view of verifiability. By examining the totality of the verification resources available to the international community it has not only given a truer picture of verifiability, but has drawn attention to the fact that this compounds the uncertainty facing any potential treaty evader. A constantly evolving, technically advancing and multi-faceted CTBT verification gauntlet is something that no state is ever likely to contemplate running.

Notes and References

1. The Commission is supported by the John Merck Fund, the Ploughshares Fund, Rockefeller Family Philanthropic Offices, and the governments of Germany and the United Kingdom.

2. Many observers believe that the CTBT is so worded as to permit a state party to submit any information from whatever source as being derived from National Technical Means. This means that a state party could submit, for instance, seismic data from the scientific seismic networks, and that developing countries without NTM of their own could submit satellite imagery purchased commercially.

Trevor Findlay is Executive Director of the Verification Research, Training and Information Centre (VERTIC) and was Chairman of the Independent Commission on the Verifiability of the CTBT. For further information on the Commission, including its Final Report and contributions of Commissioners, see www.ctbtcommission.org. For information on VERTIC see http://www.vertic.org.

Appendix: Members of the Independent Commission on the Verifiability of the CTBT

  • H.E. Ambassador Nobuyasu Abe, Permanent Mission of Japan to the United Nations, Vienna
  • Peter Basham, Provisional Technical Secretariat of the CTBT Organization, Vienna
  • Dr. Elisabeth Blanc, Commissariat à l'Energie Atomique (CEA), France
  • Dr. Ola Dahlman, Swedish Defence Research Organization (FOA), Sweden
  • Dr. Trevor Findlay, Verification Research, Training and Information Centre (VERTIC), UK (Chairman)
  • Dr. Lindsay H. Hall, Defence Operational Technology Support Establishment, New Zealand
  • Professor Herbert Huppert, Cambridge University, Institute of Theoretical Physics and Fellow of the Royal Society, UK
  • Professor Bhupendra Jasani, Department of War Studies, King' College London, UK
  • Dr. Yuriy Khokhlov, Research Institute for Pulse Technique, MINATOM, Russia
  • Peter Marshall, UK Atomic Weapons Establishment at Aldermaston, UK
  • Dr. Mordechai Melamud, Israel Atomic Energy Commission, Israel
  • Dr. Joachim Schulze, Provisional Technical Secretariat of the CTBT Organization, Vienna
  • Dr. Gregory van der Vink, Incorporated Research Institutions for Seismology (IRIS), US
  • Professor Terry Wallace, Department of Geosciences, University of Arizona, US.

© 2000 The Acronym Institute.