The Comprehensive Test Ban Treaty (CTBT) is an international treaty that obligates State Parties not to carry out any nuclear weapon test explosion or any other nuclear explosion, to prohibit and prevent nuclear explosions at any place under its jurisdiction or control, and to refrain from causing, encouraging, or participating in the carrying out of any nuclear weapon test explosion or any other nuclear explosion.

Under Article 14 of the CTBT, 44 pre-determined nuclear-capable countries must ratify the treaty before it enters into force internationally. While only 26 of these countries have ratified, the CTBT already has in place a functioning international organization and an operational and expanding verification regime.

Upon entry into force, the CTBT establishes the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) to achieve the object and purpose of the CTBT and oversee implementation, including the verification regime. The CTBTO will be composed of the Conference of the States Parties, the Executive Council, and the Technical Secretariat, and will be located in Vienna, Austria.

Each State Party has one representative in the Conference of the States Parties, which is responsible for overseeing implementation of the Treaty, the activities of the Executive Council and the Technical Secretariat, and the State Parties' compliance with the Treaty's provisions. It is charged with considering and reviewing scientific and technological developments that could affect the operation of the Treaty, and with taking the necessary measures to ensure compliance with the Treaty and to address any situation that contravenes the provisions of the Treaty. The Executive Council, consisting of 51 members elected by States Parties from 6 geographical regions, supervises the Technical Secretariat, carries out the preparatory and follow-up work for sessions of the Conference, manages the operation of agreements relating to the implementation of verification activities, and makes recommendations to the Conference on any concern raised by a State Party about possible non-compliance. The Technical Secretariat conducts on-site inspections, supervises the operation of the International Monitoring System, and coordinates the International Data Center. The Technical Secretariat is headed by a Director-General, elected by the Executive Council for a term of four years, with a 2-term limit.

In 1996, the Preparatory Commission of the CTBTO (CTBTO PrepCom) was established in order to bridge the period until the Treaty's entry into force. The CTBTO PrepCom is financed by the States Signatories and consists of a plenary body composed of all the States Signatories (the Preparatory Commission) and a Provisional Technical Secretariat. The main task of the Preparatory Commission is to establish the global verification regime so that it will be operational by the time the Treaty enters into force. The budget was US$58.4 million in 1998 and US$74.7 million in 1999.

The primary aim of verification is to increase the level of transparency to a point where a determination regarding compliance can be reliably made. In order to detect, locate and identify nuclear explosions, the CTBT establishes a global verification system, consisting of four separate but interdependent components:

• International Monitoring System;
• Consultation and clarification procedures;
• On-site inspections; and
• Confidence-building measures.

The International Monitoring System (IMS) for detecting and locating nuclear test explosions is to consist of 321 remote sensing stations and at least 16 radionuclide laboratories located in some 90 countries. The IMS employs four technologies for monitoring: seismological, radionuclide, hydroacoustical, and infrasound. Approximately one-third of the stations are already operational, gathering information 24-hours a day, 7 days a week and reporting to the Prototype International Data Center (IDC) in Arlington, Virginia, which is temporarily housing the information collected from the IMS facilities. The International Data Center in Vienna, Austria, is expected to begin serving this function by February 2000. The IMS data will be accessible to all parties to the CTBT and will provide a way for parties with no or limited technical means to participate in the verification and enforcement of the treaty. Hughes Olivetti Telecom Ltd has a $70 million contract with the CTBTO to maintain the communications infrastructure for the International Monitoring System and to ensure the flow of data from the system into the International Data Center for a ten-year period.

All four monitoring technologies have proved to be more capable than anticipated, and are continuously being updated as the IMS is being set up. The IMS was designed to detect and locate explosions down to one kiloton TNT equivalent, and has been shown to detect a test explosion of 0.1 kiloton of conventional chemical explosives conducted in Kazakhstan in August 1998. The other monitoring strategies are to be used to ensure detection below one kiloton, including on-site monitoring, which can only be applied if the Treaty enters into force.

It should be noted that relatively small nuclear explosions, ranging from a few pounds to a few hundred tons of TNT equivalent, tend to be the most technically difficult to conduct, since a minimum critical mass of fissile material is needed to set off a nuclear explosion. Hence, contrary to the impression given by some treaty opponents, there is greater technical scope for the wealthiest and most sophisticated states to conduct lower-yield, undetected tests relative to those states that do not now have proven nuclear arsenals.

Consultation and clarification are intended to provide States Parties a relatively non-confrontational and inexpensive means that may resolve concerns regarding compliance with the Treaty by requesting clarification from any other State Party on any matter that may cause concern about possible non-compliance. States Parties are not required to attempt to resolve concerns through consultation before requesting an on-site inspection.

For the purpose of clarifying whether a nuclear explosion has been carried out in violation of the treaty, each State Party has the right to request an on-site inspection. Inspections must be considered and voted on by the Executive Council within 96 hours of the request and require a 60 percent majority for approval of an inspection. Subject to the Executive Council's approval, an inspection team must be dispatched by the Technical Secretariat within 6 days to the site where an ambiguous event has been detected. The inspection team would be appointed by the Director-General of the Technical Secretariat of the CTBTO. The inspection activities range from overflight information, ground surface survey, seismic aftershock detection and location, other geophysical measurement techniques, radionuclide measurements, and drilling into the suspected underground detonation point. There has been considerable tension over the issue of on-site inspections, since military personnel in all countries are reluctant to let outside parties into their secret areas. Meanwhile, these same personnel want the most intrusive inspection procedures for other parties.

States Parties also have the right to use information obtained by national technical means to request an on-site inspection. National technical means are methods, such as satellite photographs, employed by governments to detect activities in other countries. Governments can also install their own supplementary acoustic or seismic devices in addition to the IMS. National technical means provide an additional way in which individual countries can detect suspicious activities and ask for on-site inspections. Because some countries have better technology and more money, they are in a better position to ask for on-site inspections. Since there is considerable variation in national technical capability even among nuclear weapons states, this has been an additional source of resistance to intrusive inspection. The premise is that parties with the most sophisticated and extensive national technical means would be able to request the most frequent inspections. The potential use of such inspections for espionage purposes has been a concern.

The treaty also provides for the possibility to impose sanctions. The Conference is authorized to restrict or suspend a State Party's rights and privileges under the treaty if it fails to fulfill a request by the Conference or Executive Council. The Conference may also recommend to States parties collective measures that are in conformity with international law, which include but are not limited to sanctions. The issue may also be brought to the United Nations by the Conference or, if the case is urgent, by the Executive Council.

Confidence-building measures (CBMs) are also provided for in the CTBT. CBMs are cooperative procedures that seek to reduce misperceptions and misunderstandings among State Parties by enabling them to be more transparent about their intentions in specific circumstances. For instance, because the mining industry uses explosions of hundreds of tons of TNT, a confidence building measure might include advance warning to the Technical Secretariat of such explosions.

Verification matters because the success of the CTBT in preventing proliferation among non-weapons states and in reducing the development of new weapons by weapons states depends on it. There can be no perfect guarantee against cheating, just as there can be no perfect security against nuclear weapons. All we can do is make progress. In IEER's analysis, this will come from greater cooperation and nuclear disarmament, not from more weapons or "enduring" nuclear arsenals.

Monitoring Technologies in the CTBT's International Monitoring System Seismic monitoring: This method detects the typical seismic waves created by nuclear tests. These are sharp, sudden jolts, distinguishable from earthquakes (see seismograms). If the test is very small, the seismic waves may be too weak to detect at remote stations. The seismic waves arising from the tests would get lost in the noise of tiny earth movements, both natural and artificial. According to the London-based Verification, Research, Training and Information Centre (Vertic), seismology provides the "principal and most mature verification technique for the CTBT...." The CTBTO [CTBT Organization] will have "fifty primary and 120 auxiliary seismic stations, distributed world-wide," to distinguish between earthquakes and explosions. These seismic stations will be supplemented by thousands of others around the world that are now used to detect and study natural phenomena like earthquakes. Detection of radionuclides: This method detects tests by measuring the radioactive materials, notably fission products, in the fallout. Atmospheric tests produce a great deal of fallout and so are relatively easily detected. But underground tests also result in the release of some amounts of fission products into the atmosphere, enabling detection. The CTBTO will have at least 40 radionuclide detection stations positioned around the world that will be able to detect noble gas fission products, such as xenon-133 and krypton-85 as well as radionuclides that can be trapped on filters installed at air sampling stations. There will be 16 laboratories to analyze the filters. Underwater listening devices (Hydroacoustic Network): There are to be 11 such stations, of which four are now operating. Three of the four are being run by the United States. They are useful for detecting underwater tests, but also for low-altitude atmospheric tests. Infrasound instruments : Microbarographs are special microphones that use "infrasound" and can measure air pressure changes caused by atmospheric tests. According to Vertic, while this is "is the least developed of all the [monitoring]... technologies, the broader frequency ranges now available make it potentially very sensitive. Four infrasound stations are currently reporting, three of which are in the US and one in Australia." Summarized and paraphrased with permission from U.S. Security Benefits from Test Ban Monitoring & On Site Inspections, Coalition to Reduce Nuclear Dangers Issue Brief Vol. 3 No. 14, September 27, 1999, written by Trevor Findlay and Oliver Meier of the Verification, Research, Training and Information Centre (Vertic), on the web at http://www.clw.org/coalition/briefv3n14.htm, viewed January 8, 2000.