US sheds light on its allegation of Chinese nuclear test and urges nations to push for disarmament

US Official Reveals Details of Alleged Chinese Nuclear Test, Urges Global Pressure on Arms Control

A senior U.S. arms control official has disclosed what he described as newly declassified information about a suspected Chinese underground nuclear test conducted in 2020, while calling on the international community to pressure both China and Russia toward greater nuclear disarmament efforts.

Christopher Yeaw, assistant secretary of state for arms control and nonproliferation, presented the information Monday at the UN-backed Conference on Disarmament in Geneva. His remarks come at a particularly sensitive moment, following the recent expiration of the New START treaty—the last remaining nuclear arms control agreement between the United States and Russia.

According to Yeaw, monitoring systems detected a magnitude 2.75 seismic event at China’s Lop Nur underground test site in western China on June 22, 2020. “It was a probable explosion based upon comparisons between historic explosions and earthquakes,” Yeaw stated. “The seismic signals were indicative of a single fire explosion, not typical of mining explosions.”

The U.S. official claimed China has deliberately hindered international monitoring efforts, rejecting proposals to place seismic testing stations at a comparable distance to its Lop Nur site as the U.S. allows near its Nevada test facility.

China has vehemently denied these allegations. Ambassador Jian Shen, China’s representative to the conference, called the accusations “completely unfounded” and merely a pretext for the U.S. to potentially resume its own nuclear testing. “The U.S.’s practice of smearing other countries to evade international arms control obligations seriously damages its own international standing,” Shen stated.

The diplomatic exchange highlights growing tensions in the nuclear weapons landscape. Yeaw emphasized what he characterized as China’s rapid nuclear expansion, suggesting Beijing “may achieve parity within the next four or five years.” He pointed to a significant increase in China’s nuclear stockpile, claiming it has grown from “the low 200s to more than 600” since 2020 and is projected to exceed 1,000 warheads by 2030.

Nuclear policy experts note the serious implications of these allegations. Tong Zhao, a senior fellow at the Carnegie Endowment for International Peace, observed that if China conducted yield-producing nuclear tests, it “would severely tarnish its reputation as a responsible nuclear power.” Such actions could potentially serve as justification for the U.S. to resume its own nuclear testing program, suspended since 1992.

The nuclear landscape has grown increasingly complex since former President Donald Trump indicated in October that the U.S. might resume nuclear testing. However, Energy Secretary Chris Wright later clarified that any tests would not include nuclear explosions.

The expiration of the New START treaty has created a vacuum in nuclear arms control, eliminating formal limits on the arsenals of the world’s two largest nuclear powers. Secretary of State Marco Rubio recently stated that the U.S. is “pursuing all avenues” to fulfill Trump’s “desire for a world with fewer of these awful weapons,” while insisting Washington would not remain passive as Russia and China expand their nuclear forces.

The U.S. has expressed openness to multiple diplomatic approaches, including bilateral talks, small-group discussions, or broader multilateral negotiations. “We are looking to all of you to help encourage nuclear-weapon states like China and Russia to engage meaningfully in a multilateral process,” Yeaw told the conference delegates.

Ambassador Shen countered by suggesting it was “unfair, unreasonable and unfeasible” to demand China engage in trilateral nuclear arms control talks. He maintained that China’s arsenal remains smaller than those of the U.S. and Russia, and that Beijing faces a “completely different” strategic security environment.

As diplomatic efforts continue, Yeaw is scheduled to meet with Chinese and other delegations in Geneva on Tuesday, following Monday’s discussions with Russian representatives. The talks take place against the backdrop of rising global concerns about a potential new nuclear arms race in the absence of formal controls.