The United States has accused China of conducting a covert nuclear test in 2020, marking a significant escalation in global nuclear tensions. This claim emerged as the Trump administration advocates for a comprehensive nuclear weapons agreement that would involve not only Russia but also China.
This accusation was made shortly after the expiration of the last remaining nuclear arms control treaty between the US and Russia, the New START Treaty, which ended nearly three decades of treaty-based limitations on the world’s two largest nuclear arsenals. The lapse of this treaty leaves both nations without formal constraints on their nuclear stockpiles for the first time in decades.
Details of the Alleged Nuclear Test
Thomas DiNanno, Undersecretary of State for Arms Control and International Security, revealed in Vienna at a global Disarmament Conference that the US government is aware China has engaged in nuclear explosive tests. He stated, “China conducted one such yield producing nuclear test on June 22 of 2020.” The test reportedly had yields in the hundreds of tons, though specific figures were not disclosed. DiNanno accused China of deliberately attempting to conceal these tests by using “decoupling” techniques, which involve blasting nuclear devices in large caverns to reduce seismic signals and evade detection.
Contradictory Findings from Monitoring Organizations
However, the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), responsible for monitoring nuclear weapon tests worldwide, has reported no evidence consistent with a nuclear explosion on the stated date. Rob Floyd, the CTBTO’s executive secretary, confirmed that their International Monitoring System, which can detect explosions with yields above roughly 500 tons of TNT, did not register any relevant events on June 22, 2020. Floyd also highlighted that despite the alleged test’s yield being possibly low enough to avoid detection, their systems have successfully detected all six declared nuclear tests by North Korea.
Legal and Treaty Context
The Comprehensive Nuclear-Test-Ban Treaty (CTBT) prohibits all nuclear explosions but cannot enter into force until ratified by key states, including the US and China, who have signed but not ratified it. Russia, having ratified the treaty earlier, withdrew its ratification last year. Without full ratification, the CTBT’s enforcement mechanisms remain inactive.
The US and China have maintained a mutual moratorium on nuclear testing in the past. However, President Trump explicitly called for the resumption of US nuclear testing on an “equal basis” with other powers last year. DiNanno suggested that the allegation of Chinese testing was a motivation behind this declaration.
US Nuclear Policy Post-New START
With the end of the New START Treaty, DiNanno declared “the end of US unilateral restraint,” signaling that the US will pursue ongoing nuclear modernization programs. He emphasized the US will maintain a “robust, credible, and modernized nuclear deterrent” and retain non-deployed nuclear capacity to adapt to evolving security threats. The US expresses intent to negotiate future arms control agreements involving more parties than just Russia, explicitly including China.
China’s Response and Position on Arms Control
A spokesperson for the Chinese Embassy in Washington denied these accusations, affirming China’s adherence to a policy of “no first use” and commitment to self-defense nuclear strategy. Liu Pengyu stated that China “adheres to its nuclear testing moratorium” and is willing to collaborate with all parties to uphold the CTBT and the global nuclear disarmament and non-proliferation regime. He urged the US to respect its obligations and contribute to international stability.
Challenges and Perspectives on Multilateral Arms Control
China has consistently rejected trilateral arms control negotiations, citing its smaller arsenal compared to Russia and the US. Experts argue that China’s reluctance may stem from its ambition to establish itself as a superpower nuclear force. Matthew Kroenig of the Atlantic Council noted that if China genuinely fears US nuclear expansion, it should be motivated to engage in arms control negotiations. Instead, Beijing appears reluctant, perhaps unwilling to sacrifice its growing nuclear capabilities.
Some US officials see the expiration of New START as an opportunity to expand the US arsenal strategically and potentially pressure China into the arms control talks. However, Arms Control Association Executive Director Daryl Kimball cautions that mere accusations are insufficient. He advocates for the US to pursue bilateral discussions and maintain New START’s key limits with Russia, even if the treaty has formally expired.
Summary of Current Nuclear Arms Control Dynamics
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The US accuses China of secretly testing a nuclear device in mid-2020.
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The CTBTO monitoring system reports no detected test consistent with the claim.
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The expired New START Treaty leaves US and Russian arsenals unlimited by treaty constraints.
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The Trump administration calls for broader arms control talks including China.
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China denies the allegation and emphasizes its moratorium and defensive nuclear posture.
- Challenges remain due to differences in nuclear arsenal sizes and strategic priorities.
The recent developments underscore a critical moment in international arms control, with the potential for renewed nuclear competition and diplomatic efforts to manage global security risks. The involvement of China in future arms control frameworks remains a key issue shaping nuclear policy discussions.
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