VIENNA — The fragile international consensus against nuclear weapons testing faces unprecedented strain as both the United States and Russia have issued reciprocal threats to resume atomic experiments, triggering widespread alarm among nonproliferation experts and global security analysts.
In late October, U.S. President Donald Trump declared via his Truth Social platform that he had instructed the Department of War to initiate nuclear weapons testing “on an equal basis” with other nations’ programs, asserting this process would “begin immediately.” This pronouncement prompted a swift response from Moscow, where Russian President Vladimir Putin informed his Security Council that Russia would be “under obligation to take reciprocal measures” should the U.S. or any Comprehensive Nuclear-Test-Ban Treaty (CTBT) signatory conduct nuclear tests.
The current crisis unfolds against the backdrop of the CTBT, adopted by the U.N. General Assembly in 1996 following decades of escalating concerns about atmospheric testing. Although the treaty has achieved near-universal acceptance with 187 signatories and 178 ratifications, it has never formally entered into force due to the requirement that 44 specific nuclear technology-capable states must ratify it. Nine nations remain outside the ratification framework: China, Egypt, Iran, Israel and the U.S. have signed but not ratified; India, North Korea and Pakistan neither signed nor ratified; while Russia recently revoked its ratification in 2023, citing “unacceptable” imbalance with the U.S. position.
Vienna-based Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) maintains an extensive global monitoring network comprising 307 stations utilizing seismic, hydroacoustic, infrasound and radionuclide technologies to detect nuclear explosions. With a 2025 budget exceeding $139 million, the organization has successfully detected all six North Korean tests between 2006-2017.
Arms control experts warn that resumed testing would particularly benefit nations with less nuclear testing experience. Daryl Kimball of the Arms Control Association cautioned that U.S. testing would “open the door for states with less nuclear testing experience to conduct full-scale tests that could help them perfect smaller, lighter warhead designs,” ultimately decreasing both U.S. and international security. Joseph Rodgers of the Center for Strategic and International Studies noted that countries like China and India “stand to profit from a resumption of nuclear tests” more than the U.S. or Russia, who have conducted the vast majority of the approximately 2,000 tests occurring mostly before 1996.
The nature of potential testing remains unclear. U.S. Energy Secretary Chris Wright indicated new tests would exclude nuclear explosions, referencing subcritical experiments that produce no self-sustaining chain reaction and thus don’t violate the CTBT. The treaty specifically bans supercritical tests creating nuclear yield—the energy release defining destructive power—under a zero yield standard.
Detection challenges persist for extremely low-yield hydronuclear tests conducted underground in metal chambers, which Kimball describes as creating a “verification gap.” While the monitoring system was designed to detect 1 kiloton explosions (compared to Hiroshima’s 15 kilotons), CTBTO Executive Secretary Robert Floyd noted it actually performs at approximately 500 tons TNT sensitivity.
In the current climate of uncertainty, Floyd emphasizes his organization’s role in providing “confidence to states” that they would detect any nuclear explosion “anywhere, anytime,” even as diplomatic tensions escalate between the world’s nuclear superpowers.
