In a significant disclosure from 2020 that continues to resonate in 2025, United States officials accused China of conducting a clandestine nuclear test in June 2020. This serious allegation emerged as the Trump administration advocated for a comprehensive new arms control agreement that would encompass both China and Russia, aiming to redefine global nuclear limitations. The claim, made during a period of heightened geopolitical tension, highlighted deep concerns within Washington regarding Beijing’s transparency on its nuclear activities and broader strategic intentions, particularly in the vacuum created by the instability of existing treaties. This historical accusation remains a critical point of reference for current discussions on nuclear non-proliferation and the challenges of verifiable disarmament among major world powers.
The accusation originally surfaced a day after the critical New START treaty between the US and Russia was nearing its formal expiration, an event that would leave the world’s largest nuclear superpowers without binding limits on their arsenals for the first time since the Cold War. While the treaty was extended in 2021 and Russia suspended its participation in 2023, the sentiment of an unconstrained arms race has significantly shaped the current strategic environment in 2025.
President Donald Trump’s administration, along with other high-ranking officials, had previously signaled a reluctance to adhere indefinitely to the New START limitations, pushing instead for a broader accord to address perceived threats from both Moscow and Beijing. This included an earlier call from Trump for the United States to resume its own nuclear weapons testing, provided it was on “equal footing” with other nations.
Unveiling the 2020 allegations: a look back at China’s secret nuclear test claims
During a speech at the Global Conference on Disarmament in Vienna on May 5, 2020, Thomas DiNanno, the then-Undersecretary of State for Arms Control and International Security, explicitly stated that the U.S. government possessed intelligence indicating China had carried out “nuclear explosive tests,” including preparations for tests with yields estimated “in the hundreds of tons.”
DiNanno pinpointed June 22, 2020, as the date of a specific “nuclear test with energy output” by China, though he offered no further immediate details. An unnamed former senior U.S. official later confirmed that the intelligence regarding this alleged Chinese test had been declassified, underlining the gravity with which the US government viewed the information.
The delicate state of arms control in 2025
DiNanno further alleged that the Chinese military had actively attempted to “conceal the tests by obscuring the nuclear explosions,” implying a deliberate effort to circumvent existing commitments against such activities. This method, known as “decoupling,” involves excavating large caverns to reduce the seismic signature of a nuclear explosion, making it significantly harder to detect through conventional monitoring systems.
In response to the 2020 accusation, Rob Floyd, Executive Secretary of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), issued a statement noting that the organization’s International Monitoring System (IMS) had “not detected any event consistent with the characteristics of a nuclear weapon test explosion” on June 22, 2020. Subsequent, more detailed analyses by the CTBTO also failed to alter this conclusion, leading to ongoing debate about the validity and detectability of such low-yield tests.
The CTBTO’s IMS is designed to detect nuclear test explosions with a yield equivalent to or exceeding approximately 500 tons of TNT. Given DiNanno’s assertion that the alleged Chinese test had a yield “in the hundreds of tons,” it remains unclear whether the event would have surpassed the detection threshold of the international monitoring system, adding a layer of complexity to the verification challenge. Experts suggest that extremely low-yield explosions could potentially bypass current monitoring networks.
Beijing’s denial and strategic stance
The Treaty on the Prohibition of Nuclear Weapons (TPNW), while broadly supported globally, still faces challenges with key nuclear powers. The Comprehensive Nuclear-Test-Ban Treaty (CTBT) itself prohibits “any nuclear weapon test explosion or any other nuclear explosion.” However, the treaty cannot formally enter into force until all 44 Annex 2 states, including the US and China, ratify it. While both nations signed the CTBT, they have yet to ratify it, and Russia notably withdrew its ratification in 2023, further complicating the international non-proliferation regime.
In 2020, in response to the US allegations, a spokesperson for the Chinese Embassy in Washington, D.C., affirmed China’s consistent adherence to a “no first use” policy regarding nuclear weapons and a self-defense-oriented nuclear strategy. The spokesperson reiterated China’s commitment to its nuclear testing moratorium, emphasizing its readiness to collaborate with all parties to uphold the authority of the CTBT and safeguard the international nuclear disarmament and non-proliferation framework.
Detection challenges and monitoring capabilities
The historical U.S. annual compliance report from 2020 had previously assessed that Russia failed to comply with its testing moratorium by conducting “supercritical nuclear weapon tests,” highlighting a pattern of concerns extending beyond China. These past assessments contribute to the current landscape of distrust and the perceived need for updated arms control mechanisms in 2025.
DiNanno’s statements in 2020 implied that the alleged Chinese tests could have influenced the Trump administration’s call for renewed U.S. nuclear weapons testing, suggesting a reciprocal action in response to perceived violations by competitors. This perspective underscores the tit-for-tat dynamic that often characterizes international arms control discussions.
The future of nuclear deterrence: a US perspective
The U.S. has consistently maintained a robust nuclear deterrence posture to ensure its security and preserve global peace and stability. This involves continuous modernization programs for its nuclear arsenal, many of which began during the period when the New START treaty was still fully operational. The current scenario, marked by the strained status of New START, allows the U.S. to maintain non-deployed nuclear capabilities that could be utilized if the president determines it necessary to address evolving security threats.
U.S. officials anticipate that the next era of arms control negotiations must broaden its scope beyond just Russia to include other significant nuclear powers. The strategic environment of 2025 necessitates a multi-lateral approach to maintain global stability, moving past the bilateral frameworks that defined much of the Cold War era and its aftermath.
China’s rejection of trilateral negotiations
Peking has consistently rejected calls for trilateral arms control negotiations, arguing that its nuclear arsenal is not comparable in scale to those of the United States and Russia. This stance has been a recurring impediment to efforts aimed at drawing China into formal arms limitation talks, creating a significant challenge for future global security frameworks.
Experts like Matthew Kroenig, a senior fellow at the Atlantic Council, question China’s reasoning, suggesting that if the size of its arsenal is a genuine concern, then arms control should be in its interest. He believes China’s reluctance stems from a desire to achieve superpower nuclear status and is not prepared to negotiate away significant investments in its nuclear force development.
Expert insights on the evolving landscape
Some U.S. government officials, according to insights from 2020, believed that the eventual expiration of New START would create an opportunity to expand the American nuclear arsenal, potentially generating enough concern in China to compel them to the negotiating table. This strategic thinking highlights a coercive approach to arms control, leveraging military strength to encourage diplomatic engagement.
Daryl Kimball, Executive Director of the Arms Control Association, emphasized the seriousness of any genuine violation of a nuclear test ban treaty. He stressed that merely raising complaints does not resolve the underlying issue. Kimball urged the U.S. to propose a “sensible approach,” such as bilateral arms control negotiations, while also advocating for continued adherence to the core limits of New START by both the United States and Russia, despite the treaty’s current vulnerabilities.
