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Review and Update: Technical Issues Related to the
Comprehensive Nuclear Test Ban Treaty


The Comprehensive Test Ban Treaty (CTBT) was first considered by the U.S. Senate in 1999, but failed to gain the required two-thirds majority and was not ratified. Opponents of ratification argued that the complex treaty required many months for adequate examination, but that instead the debate was abrupt and truncated, highly politicized and lacked technical input. The debate demonstrated a lack of confidence in verification and enforcement provisions, uncertainty over whether the U.S. stockpile could be safely and reliably maintained without testing, and whether the proposed international monitoring system could detect tests at a low enough yield to eliminate militarily useful detonations. In April 2000, at the request of General John Shalikashvili, then Special Advisor to the President and the Secretary of State for the Comprehensive Test Ban Treaty (CTBT), the National Academy of Sciences (NAS) was charged with reviewing the key technical concerns raised during the Senate debate of October 1999 on ratification of the CTBT.

In the resulting 2002 report, Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty, the NAS Committee on Technical Issues Related to the Ratification of the Comprehensive Nuclear Test Ban Treaty reviewed and assessed the three key technical issues that arose during the Senate debate over treaty ratification in 1999: 1) Confidence in the safety and reliability of the U.S. nuclear stockpile (as well as its weapon design/evaluation capabilities) absent nuclear testing; 2) Capabilities of the international nuclear-test monitoring system and; 3) Additions to nuclear-weapon capabilities other countries could achieve through undetected nuclear testing and their potential effect on U.S. security. That study is still considered by many to be the benchmark technical analysis of the CTBT.

Current Project

An ad hoc committee of the National Academies will review and update aspects of the analysis in the 2002 National Academies’ report, Technical Issues Related to the Comprehensive Nuclear-Test Ban Treaty, drawing on the latest evidence in each of the following areas:

1) Maintaining the safety and reliability of the U.S. stockpile. The committee will assess, including information developed for and produced by the Nuclear Posture Review, the Administration’s plan to manage the risks in ensuring, over the longer term, a safe and reliable nuclear weapons stockpile absent underground nuclear testing. The experience of the U.S. stockpile stewardship program, particularly in the last decade, will also be taken into account.

2) Nuclear explosion detection, location and identification. The committee will assess present nuclear explosion detection capabilities, taking into account the totality of assets accessible to the United States, including: (a) any improvements in U.S. national technical means in the last decade, and (b) operating experience of the international monitoring system. The committee might also consider how these capabilities are expected to improve over time.

3) Sustainability. The committee will assess what commitments are required to sustain: (a) America’s nuclear stockpile; (b) the U.S. monitoring system; and (c) an adequate international verification regime, including On-Site Inspection.

4) Technical Advances. The committee will assess the potential technical advances to nuclear weapon capabilities for other countries: (a) that result from evasive and non-evasive testing at levels below the U.S. detection capability; and (b) that result from returning to full-yield testing in a non-test-ban environment.

A Seismology Subcommittee was separately constituted for the purpose of providing input to the parent Committee to Review and Update “Technical Issues Related to the Comprehensive Nuclear Test Ban Treaty (CTBT).”  The Subcommittee will produce written input on seismology issues that have been identified by the CTBT Committee and will interact with the CTBT Committee as needed.  The Subcommittee may also raise issues to the CTBT Committee that in its view have a material bearing that the Committee may not have identified.  In addition to including the Subcommittee’s input in the Committee’s report, the Committee may also choose to use the Subcommittee’s material as appendices that further explain certain issues in the report.

An unclassified and classified version of the study will be issued to permit a complete evaluation of the evidence on these points.

This project is sponsored by the National Academies, the Department of State, and the Department of Energy.

Please email for additional information. Please include “CTBT” in the email subject line.