Department Seal The CTBT is Effectively Verifiable
Fact Sheet released by the Bureau of Arms Control,
U.S. Department of State, Washington, DC, October 8, 1999

  • The U.S. nuclear-test monitoring and verification regime is composed of a diverse array of national and international capabilities that facilitate effective verification of compliance with the CTBT.
  • The CTBT itself establishes a far-reaching verification regime, which includes an International Monitoring System of sensors capable of monitoring for nuclear explosions underground, underwater, and in the atmosphere.
  • The monitoring challenges presented by the wide scope of the CTBT exceed those imposed by any previous nuclear test-related treaty. Our current capability to monitor nuclear explosions will undergo significant improvement over the next several years to meet these challenges.
  • While no Treaty is 100% verifiable, and while we have identified possible evasion scenarios, we believe our National Intelligence Means, together with the Treaty's verification regime and our diplomatic efforts, provides the United States with the means to make the CTBT effectively verifiable.
  • The Treaty is effectively verifiable because of the significant probability of detection by the global system of 321 Treaty-required monitoring stations in combination with other national and international monitoring networks, and the deterrent that the verification regime, including on-site inspection, provides. These provide a threat of a very high cost to a potential evader.
  • The CTBT verification regime will provide information of importance to meeting our non-proliferation and nuclear-test monitoring and verification requirements.
  • With this information, we can do a better job of detecting and deterring nuclear tests, and responding to potential violations of the Treaty.
  • This information will help provide the means to assess whether the Treaty is constraining the proliferation of nuclear weapons and deterring the conduct of nuclear explosions (in terms of yields and numbers of tests) that could damage U.S. security interests.
  • Our judgment that the CTBT is effectively verifiable reflects the belief that U.S. nuclear deterrence would not be undermined by possible nuclear explosive testing that the United States might fail to detect.
  • Effective verification does not provide a guarantee that all tests under all circumstances will be detected. It does provide a guarantee that U.S. security is protected.

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