U.S. Accuses China of Secret Nuclear Test, Raising Arms Race Fears

Washington presents evidence of alleged 2020 underground blast at Lop Nur site, which Beijing firmly denies

Published on Feb. 23, 2026

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A senior U.S. official has presented what Washington describes as declassified evidence of a secret Chinese underground nuclear test conducted in 2020, intensifying an already fraught global arms control debate. The disclosure, made at the United Nations-backed Conference on Disarmament in Geneva, came just weeks after the last remaining nuclear arms treaty between the U.S. and Russia expired, leaving the world's major nuclear powers operating without formal limits on their arsenals for the first time in decades.

Why it matters

The U.S. accusation against China comes amid a rapidly shifting nuclear landscape, with Beijing believed to have significantly expanded its nuclear arsenal in recent years. The expiry of the New START treaty has left the U.S. and Russia without any formal limits on their nuclear weapons, raising concerns about a potential new arms race among the world's major nuclear powers.

The details

Christopher Yeaw, Assistant Secretary of State for the Bureau of Arms Control and Nonproliferation, pointed to a magnitude 2.75 seismic event detected on June 22, 2020 by an international monitoring station in Kazakhstan, which he said originated from China's Lop Nur underground test site. Yeaw described the signals as 'indicative of a single fire explosion, not typical of mining explosions.' Beijing has firmly denied the allegation, with China's ambassador to the Conference on Disarmament accusing the U.S. of 'continued distortion and smearing of China's nuclear policy.'

  • On June 22, 2020, a magnitude 2.75 seismic event was detected by an international monitoring station in Kazakhstan.
  • The U.S. official presented the evidence at the United Nations-backed Conference on Disarmament in Geneva on Monday.

The players

Christopher Yeaw

Assistant Secretary of State for the Bureau of Arms Control and Nonproliferation, who presented the U.S. evidence of the alleged Chinese nuclear test.

Jian Shen

China's ambassador to the Conference on Disarmament, who rejected the U.S. allegations as 'completely unfounded.'

Dmitry Peskov

Kremlin spokesman, who stated that 'neither the Russian Federation nor China has conducted any nuclear tests.'

Tong Zhao

A senior fellow at the Carnegie Endowment for International Peace who studies China's nuclear weapons program, and said he takes the U.S. claims seriously.

Ben Dando

Head of seismology and verification at NORSAR, a Norwegian organization that monitors for possible nuclear tests, who said the ratios of different seismic waves are consistent with an explosion, though he did not immediately agree with the full U.S. assessment.

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What they’re saying

“I can reveal that the US government is aware that China has conducted nuclear explosive tests, including preparing for tests with designated yields in the hundreds of tons.”

— Christopher Yeaw, Assistant Secretary of State for the Bureau of Arms Control and Nonproliferation (ibtimes.co.uk)

“The US accusation that China conducted a nuclear explosion test is completely unfounded and is merely a pretext for resuming its own nuclear testing.”

— Jian Shen, China's ambassador to the Conference on Disarmament (ibtimes.co.uk)

“Neither the Russian Federation nor China has conducted any nuclear tests.”

— Dmitry Peskov, Kremlin spokesman (ibtimes.co.uk)

What’s next

The judge in the case will decide on Tuesday whether or not to allow Walker Reed Quinn out on bail.

The takeaway

The U.S. accusation against China highlights the rapidly shifting nuclear landscape, with the expiry of the New START treaty leaving the world's major nuclear powers operating without formal limits on their arsenals. This raises concerns about a potential new arms race as China is believed to have significantly expanded its nuclear capabilities in recent years.