U.S. Alleges China Conducted Secret Nuclear Test in 2020

China denies the claim, calling it an attempt to 'fabricate excuses' for U.S. nuclear testing.

Published on Feb. 21, 2026

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A senior U.S. official revealed new details about an alleged underground nuclear test blast that China conducted in June 2020. The official said a remote seismic station in Kazakhstan measured an 'explosion' of magnitude 2.75 at the Lop Nor test grounds in western China. China has denied the allegation, calling it an attempt to 'fabricate excuses' for the U.S. to resume nuclear testing.

Why it matters

The allegation, if true, would mark the first time China has conducted a nuclear test since 1996 and could heighten tensions between the U.S. and China over nuclear weapons. It also comes as the U.S. is pressing China to join negotiations for a new nuclear arms control treaty to replace the expired New START agreement with Russia.

The details

According to the U.S. official, the remote seismic station in Kazakhstan measured an 'explosion' on June 22, 2020 that was not consistent with a mining blast or earthquake. The official said the data indicated it was likely a nuclear test, though the Comprehensive Test Ban Treaty Organization said there was insufficient data to confirm the allegation with confidence. China has denied the claim, calling it an attempt to 'fabricate excuses' for the U.S. to resume nuclear testing.

  • The alleged nuclear test occurred on June 22, 2020.

The players

Christopher Yeaw

A senior U.S. official and former intelligence analyst and defense official who holds a doctorate in nuclear engineering.

Robert Floyd

The executive secretary of the Comprehensive Test Ban Treaty Organization, which operates the global monitoring system that detected the seismic events.

Liu Pengyu

A spokesperson for the Chinese embassy in Washington who denied the allegation and called it an attempt to 'fabricate excuses' for U.S. nuclear testing.

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What they’re saying

“I've looked at additional data since then. There is very little possibility I would say that it is anything but an explosion, a singular explosion.”

— Christopher Yeaw, Senior U.S. Official (nbcnews.com)

“This is political manipulation aimed at pursuing nuclear hegemony and evading its own nuclear disarmament responsibilities.”

— Liu Pengyu, Chinese Embassy Spokesperson (nbcnews.com)

What’s next

The Comprehensive Test Ban Treaty Organization said it does not have enough data to confirm the U.S. allegation with confidence, and the issue is likely to continue to be a point of contention between the U.S. and China.

The takeaway

This allegation, if true, would mark a significant escalation in the nuclear tensions between the U.S. and China, potentially derailing efforts to negotiate a new nuclear arms control treaty and raising the specter of a renewed nuclear arms race.