December 11, 2025
By Daryl G. Kimball
Executive Director, Arms Control Association
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Three decades after the conclusion of the 1996 Comprehensive Test Ban Treaty (CTBT), the treaty has near universal support and has established a global norm against nuclear test explosions. The treaty is backed by a robust technical organization, the Comprehensive Test Ban Treaty Organization (CTBTO), that is responsible for the operation and maintenance of a highly sensitive global nuclear test monitoring system to detect and deter violations of the treaty.
The nuclear testing taboo impedes the development of new and more advanced nuclear warhead designs, which helps prevent dangerous nuclear competition and strengthens international security.
But the CTBT and the de facto global nuclear test moratorium cannot be taken for granted. The treaty has not yet entered into force due to the failure of eight key states, including the United States and China, to ratify, and Russia’s decision to “de-ratify” in 2023. Although all 187 signatories are legally bound to respect the central purpose of the treaty, the full benefits of the treaty—including the option to order short-notice on-site inspections to investigate potential violations—cannot be realized until it enters into force.
To keep the door to nuclear testing closed, responsible states need to rejuvenate efforts achieve entry into force of the treaty and actively resist any move to resume nuclear testing by any state.
SUMMARY OF KEY POINTS
- The CTBT has been a central goal of the nuclear Nonproliferation Treaty (NPT) states-parties since the NPT was opened for signature in 1968.
- The 1996 CTBT has brought the era of nuclear testing to an end and established a global norm against any kind of nuclear test explosion.
- The door to nuclear testing remains open as the treaty has not entered into force due to the treaty’s onerous Article XIV provisions, which require ratification by 44 specific states.
- Despite the fact that the United States has signed the CTBT and the U.S. nuclear weapons laboratory directors and the National Nuclear Security Administration have determined that nuclear explosive testing is not necessary to maintain the reliability of the U.S. nuclear arsenal, the Trump administration has declared that it will not seek Senate advice and consent for U.S. ratification and, in October 2025, Trump suggested that he would order the resumption of U.S. nuclear testing “on an equal basis.”
- Pending CTBT entry into force, the P5 should engage in technical talks to develop confidence building measures to resolve real or potential concerns about very low-yield, supercritical nuclear test detonations at former nuclear test sites.
- NPT states parties should approve stronger language in support of the global moratorium on nuclear testing and the CTBT, and the P5 should issue their own joint declaration in support of the global moratorium on nuclear testing and the CTBT ahead of the 2026 NPT Review Conference.