The Comprehensive Nuclear-Test-Ban Treaty (CTBT) has not yet entered into force, and recent developments are dominated by ongoing geopolitical tensions and the persistent holdout of nine specific states required for its enforcement. Russia's 2023 de-ratification is a major recent setback, though a global norm against testing remains. 

Key Latest Developments

• Treaty Status: As of late 2025, the CTBT has been signed by 187 states and ratified by 178. However, it requires ratification by all 44 "Annex 2" states (those possessing nuclear power or research reactors at the time of negotiation) to enter into force.
• Nine Holdout States: Nine Annex 2 states have yet to take the necessary action:
  • Signed but not ratified: China, Egypt, Iran, Israel, and the United States.
  • Not signed: India, North Korea, and Pakistan.
  • De-ratified: Russia withdrew its ratification in November 2023 to match the US's posture, though it remains a signatory and has pledged to maintain its testing moratorium unless the US tests.

• Continued Moratoriums and Concerns: Despite the lack of formal entry into force, a strong de facto global norm against nuclear testing exists, with only North Korea conducting nuclear tests this century.

• The CTBTO Executive Secretary, Robert Floyd, issued a statement on October 30, 2025, acknowledging recent public remarks about potential nuclear testing and reiterating that the International Monitoring System (IMS) stands ready to detect any such explosion, emphasizing the harmful and destabilizing impact any test would have.
• Recent conferences, such as the 14th Conference on Facilitating the Entry into Force in September 2025, highlighted the urgent need for political will and courage to accelerate the ratification process amidst a complex global security environment.

• Verification System: The CTBTO continues to build its robust verification regime, which includes a global network of over 300 monitoring stations (seismic, hydroacoustic, infrasound, and radionuclide) that have successfully detected all six declared North Korean nuclear tests. This system provides data to member states and offers additional benefits like tsunami warnings and climate research. 

The CTBT remains a cornerstone of global non-proliferation efforts, but its full legal effectiveness hinges on the political will of the remaining Annex 2 states.

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