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The CTB Treaty: A Historic Opportunity To Strengthen the Non-Proliferation Regime

CTB Treaty Executive Summary

The Comprehensive Test Ban (CTB) treaty will prohibit all nuclear weapon test explosions or other nuclear explosions anywhere in the world. In order to verify compliance with its provisions, the treaty establishes a global network of monitoring facilities and allows for on-site inspections of suspicious events. The overall accord contains a preamble, 17 treaty articles, two treaty annexes, and a protocol with two annexes detailing verification procedures.



The preamble, which lists disarmament principals and objectives, sets the overall political context of the treaty. In particular, it stresses the need for the continued reduction of nuclear weapons worldwide with the ultimate goal of their elimination. Also of significance, the preamble recognizes that a CTB will constitute an effective measure of nuclear disarmament and non-proliferation by “constraining the development and qualitative improvement of nuclear weapons and ending the development of advanced new types of nuclear weapons.” It further recognizes that a test ban will constitute “a meaningful step in the realization of a systematic process to achieve nuclear disarmament.”



Article I establishes that all states-parties are prohibited from conducting “any nuclear weapon test explosion or any other nuclear explosion.” On the basis of the negotiating record, this is understood to include all nuclear explosions with yields greater than zero, in accordance with President Bill Clinton’s August 1995 proposal. (See ACT, September 1995)


Implementing Organization

Article II establishes the Comprehensive Nuclear Test Ban Treaty Organization, which will ensure treaty implementation and provide states-parties with a forum for consultation and cooperation. The organization will consist of a Conference of the States Parties, an Executive Council and a Technical Secretariat. The organization-to be located in Vienna-will be structurally independent from, but operating in collaboration with, the International Atomic Energy Agency (IAEA).

The Conference of the States Parties-the overall governing body of the organization-will handle treaty-related policy issues and oversee the treaty’s implementation, including the activities of the Executive Council and the Technical Secretariat. The conference will meet once a year, unless otherwise decided.

The Executive Council, which will meet regularly and act as the treaty’s principal decision-making body, will consist of 51 members. In an attempt to distribute membership evenly throughout the world, the Executive Council will comprise 10 states-parties from Africa; seven from Eastern Europe; nine from Latin America and the Caribbean; seven from the Middle East and South Asia; ten from North America and Western Europe; and eight from Southeast Asia, the Pacific and the Far East. The states in each of these geographical regions are listed in Annex 1 to the treaty.

The members of the council will be elected by the conference. In order to ensure that those countries with a vested interest in a CTB are adequately represented in the council, at least one-third of the seats allotted to each region will be filled by states-parties on the basis of their nuclear capabilities applicable to the treaty, such as the number of monitoring facilities they contribute to the International Monitoring System (IMS). One seat allocated to each region will be designated on the alphabetical basis and the remaining seats will be determined by rotation or elections. Thus, each state-party will eventually have the right to serve on the council.

The Technical Secretariat will be the primary body responsible for implementing the treaty’s verification procedures. In this capacity, it will supervise the operation of the IMS and receive, process, analyze and report on the system’s data. It will also manage the International Data Center (IDC) and perform a series of procedural tasks related to conducting on-site inspections.

Article III requires each state-party, in accordance with its constitutional process, to take any necessary measures to implement its treaty obligations.


Verification and Compliance

Article IV and the verification protocol establish the treaty’s verification regime, which will consist of four basic elements: the IMS, consultation and clarification, on-site inspections and confidence-building measures. The verification regime will not be completely operational until the treaty enters into force. For instance, on-site inspections cannot be authorized until the treaty formally comes into effect.

The purpose of the IMS is to detect and identify nuclear explosions prohibited under Article I. The monitoring system will comprise a network of 50 primary and 120 auxiliary seismological monitoring stations designed to detect seismic activity and distinguish between natural events, such as earthquakes, and nuclear explosions. In addition, the system will incorporate 80 radionuclide stations and 16 radionuclide laboratories that seek to identify radioactive particles released during a nuclear explosion. The IMS will also include 60 infrasound (acoustic) and 11 hydroacoustic stations designed to pick up the sound of a nuclear explosion conducted in the atmosphere or underwater, respectively. The host state and the location of each facility is listed in Annex 1 to the protocol.

Information collected by the IMS will then be transmitted to the IDC-an essential part of the Technical Secretariat responsible for data storage and processing. Because the IMS will generate an enormous amount of raw data, the IDC will regularly provide states-parties with a number of services designed to help them monitor compliance with the treaty’s provisions. In this regard, the data center will produce integrated lists of all signals picked up by the IMS, as well as standard event lists and bulletins. In accordance with the parameters outlined in Annex 2 to the protocol, the center will also generate standard screened event bulletins that filter out those events that appear to be of a non-nuclear nature. However, notwithstanding this analysis role, the IDC must make both the raw and processed information available to all states-parties.

The consultation and clarification component of the verification regime encourages states-parties to attempt to resolve, either among themselves or through the organization, possible instances of non-compliance before requesting an on-site inspection. A state-party must provide clarification of an ambiguous event within 48 hours of receiving such a request from another state-party or the Executive Council.

If a suspicious occurrence cannot be resolved through consultation and clarification, each state-party has the right to request an on-site inspection in the territory of the party in question. The inspection request must be based on information collected by the IMS; data obtained through national technical means (NTM) of verification, such as satellites, in a manner consistent with international law (for example, not based on espionage); or a combination of IMS and NTM information. The request must contain the approximate geographical coordinates and the estimated depth of the ambiguous event, the proposed boundaries of the area to be inspected (not to exceed 1,000 square kilometers), the state-party or parties to be inspected, the probable environment and estimated time of event, all evidence upon which the request is based, the identity of the proposed observer (if available) and the results of the consultation and clarification process.

The Executive Council will make a decision on the on-site inspection request within 96 hours of its receipt from the requesting state-party. The inspection will be authorized to proceed if it has been approved by at least 30 of the council’s 51-members, the so-called “green light” procedure. An inspection team will arrive at the point of entry within six days of the council’s receipt of the inspection request. During the course of the inspection, the inspection team may submit a proposal to begin drilling, which must be approved by 26 council members. The duration of the inspection must not exceed 60 days, but may be extended by a maximum of 70 additional days (subject to council approval) if the inspection team determines that more time is needed to fulfill its mandate.

If the Executive Council rejects an on-site inspection request (or terminates an inspection already underway) because it is of a frivolous or abusive nature, the council may impose punitive measures on the requesting state-party. In this regard, it may require the requesting state-party to provide financial compensation for preparations made by the Technical Secretariat and may suspend the party’s right to request an inspection and serve on the council for an unspecified period of time.

The verification regime also incorporates confidence-building measures intended to promote treaty compliance. In order to reduce the likelihood that verification data may be misconstrued, each state-party will voluntarily provide the Technical Secretariat with notification of any chemical explosion involving a magnitude of 300 tons or more of TNT-equivalent on its territory. Each state-party may also assist the Technical Secretariat in the calibration of IMS stations.

In order to ensure compliance with the treaty’s provisions, Article V empowers the conference to revoke a state-party’s rights under the treaty, recommend to the states-parties punitive measures such as sanctions or bring the case to the attention of the United Nations. Article VI describes the mechanism by which disputes pertaining to the application or interpretation of the treaty may be settled.


Amendment Process

Under Article VII, each state-party has the right to propose amendments to the treaty after its entry into force. The proposed amendment requires the approval of a simple majority of states-parties at an amendment conference with no party casting a negative vote.


Peaceful Nuclear Explosions

Under Article VIII, a conference will be held 10 years after the treaty’s entry into force to review the implementation of its provisions, including the preamble. At this review conference, any state-party may request that the issue of so-called “peaceful nuclear explosions” (PNEs) be put on the agenda. However, the presumption is that PNEs remain prohibited unless certain virtually insurmountable obstacles are overcome. First, the review conference must decide without objection that PNEs may be permitted, then an amendment to the treaty must also be approved without objection at a separate amendment conference, as is explained above. This “double hurdle” makes it extremely unlikely that peaceful nuclear explosions will ever be permitted under the treaty.


Duration and Withdrawal

Under Article IX, the CTB treaty will be of unlimited duration. In addition, each state-party has the right to withdraw from the treaty if it decides, “extraordinary events related to the subject matter of this Treaty have jeopardized its supreme interests.” Notice of intent to withdraw must be given at least six months in advance.


Miscellaneous Provisions

Article X specifies that the treaty’s annexes, protocol and annexes to the protocol are a formal party of the treaty. Article XI declares that the treaty is open to all states for signature prior to its entry into force. Article XII maintains that each signatory state will ratify the treaty according to its own constitutional procedures. Under Article XIII, any state that has not signed the treaty prior to its entry into force may accede to it any time thereafter.


Entry into Force

Under Article XIV, the treaty will not enter into force until it has been signed and ratified by 44 states-including the five nuclear weapons states (United States, Russia, Britain, France and China) and the three “threshold states” (India, Israel and Pakistan)-listed by name in Annex 2 to the treaty. (Actual entry into force will occur 180 days after all 44 states deposit their instruments of ratification with the UN secretary-general.) The 44 states, all of which are participating members of the recently expanded Conference on Disarmament, possess nuclear power and research reactors as determined by the IAEA.

If the treaty has to come into effect “three years after the date of the anniversary of its opening for signature,” then a conference may be held for those states that have already deposited their instruments of ratification to “decide by consensus what measures consistent with international law may be undertaken to accelerate the ratification process.” However, this conference-to be repeated annually until the treaty’s entry into force-will not have the authority to waive the original provision requiring ratification by the 44 states.


Other Provisions

Article XV stipulates that the treaty’s provisions will not be subject to reservations. Article XVI establishes the UN secretary-general as the depositary of the treaty. Under Article XVII, the treaty will be authentic in six languages.

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