China's Nuclear Test Denial Deepens US-China Trust Crisis

Last Friday in Geneva, a packed arms control conference fell silent as Thomas DiNanno, the US undersecretary of state for arms control and international security, delivered a bombshell accusation. "The US government is aware that China has conducted nuclear testing," he declared, referring to alleged activities in 2020. The room's atmosphere shifted instantly from diplomatic routine to high-stakes confrontation.

China's response was swift and fierce. Foreign ministry spokesman Lin Jian fired back Wednesday, calling the US claims persistent attempts to "distort and smear China's nuclear policy." More provocatively, he framed the allegations as "an excuse" for America to justify its own potential return to nuclear testing—a charge that cuts to the heart of global nuclear governance.

The Evidence Gap

The dispute centers on what the US describes as "very low-level" nuclear testing at China's Lop Nor site in Xinjiang in 2020. If true, this would violate the Comprehensive Test Ban Treaty (CTBT), which China signed in 1996 and has claimed to honor ever since.

But here's the problem: the US hasn't provided concrete evidence, and China vehemently denies any wrongdoing. China's last acknowledged nuclear test was in July 1996, and Beijing insists it has maintained a moratorium since then. Without verification from international bodies like the International Atomic Energy Agency or the Comprehensive Test Ban Treaty Organization, the world is left to navigate competing claims.

This evidence gap isn't just a diplomatic inconvenience—it's emblematic of the broader challenge facing nuclear diplomacy in an era of strategic competition.

Why Now?

The timing of this public accusation, four years after the alleged incident, reveals strategic calculation. The US appears to be leveraging every available pressure point against China as their strategic rivalry intensifies across multiple domains.

China's nuclear modernization provides context for American concerns. While China maintains approximately 350 nuclear warheads compared to America's 5,550 and Russia's 6,255, the Pentagon estimates China could expand its arsenal to 1,000 warheads by 2030. This rapid buildup, combined with China's refusal to engage in trilateral arms control talks, has heightened US anxiety about nuclear competition.

The broader geopolitical backdrop matters too. With Russia's nuclear threats during the Ukraine war and growing concerns about a potential Taiwan conflict, nuclear issues have gained renewed urgency in Washington's strategic planning.

The Trust Deficit

This dispute illuminates a fundamental problem in nuclear diplomacy: the erosion of trust between major powers. The US has repeatedly called for greater transparency in China's nuclear program and urged Beijing to join arms control negotiations. China, however, maintains that the US and Russia should first drastically reduce their much larger arsenals before expecting constraints on smaller nuclear powers.

The result is a diplomatic stalemate. China suspended nuclear talks with the US earlier this year, citing American arms sales to Taiwan. Now, with allegations of secret testing in the mix, the prospects for productive dialogue appear even dimmer.

Global Implications

The ripple effects extend far beyond US-China relations. For allies like South Korea and Japan, questions about China's nuclear capabilities directly impact their security calculations and defense planning. For the broader international community, the dispute threatens to undermine the already fragile global nuclear order.

The CTBT, which prohibits all nuclear testing, has never entered into force because key countries including the US and China haven't ratified it. If major powers can't even agree on basic facts about compliance, the treaty's future looks increasingly uncertain.

Meanwhile, other nuclear-armed states are watching closely. If the US and China can't manage their nuclear relationship, what hope is there for broader disarmament efforts?

The Verification Challenge

Perhaps most troubling is what this dispute reveals about the limits of nuclear verification. Despite decades of investment in monitoring technology, the international community still struggles to definitively determine whether low-level nuclear activities constitute treaty violations.

This ambiguity creates space for both genuine misunderstanding and deliberate manipulation. Countries can push boundaries while maintaining plausible deniability, while accusers can make claims without providing conclusive proof. The result is a nuclear diplomacy increasingly characterized by suspicion rather than cooperation.