US Says China Conducted 'Secret Nuclear Test' Days After 2020 Galwan Clash

Washington: The United States has accused China of conducting "secret nuclear explosive tests" in June 2020, just days after the deadly clash at Galwan Valley in eastern Ladakh, where 20 Indian soldiers were killed.

Who has revealed this information?

In a post on X, US Under Secretary of State Thomas G DiNanno revealed this during a United Nations conference on disarmament in Geneva on Friday.

Thomas G DiNanno claimed that China conducted one such "yield-producing nuclear test" on June 22, 2020, just seven days after India and China face-off in eastern Ladakh. 

The US official also said that China used a technique called "decoupling" to dodge detection by global agencies

"China has conducted nuclear explosive tests, including preparing for tests with designated yields in the hundreds of tons...China has used decoupling – a method to decrease the effectiveness of seismic monitoring – to hide its activities from the world. China conducted one such yield producing nuclear test on June 22, 2020," DiNanno wrote.

China has conducted nuclear explosive tests, including preparing for tests with designated yields in the hundreds of tons… China has used decoupling – a method to decrease the effectiveness of seismic monitoring – to hide its activities from the world. China conducted one such…

— Under Secretary of State Thomas G. DiNanno (@UnderSecT) February 6, 2026

What happened in June 2020?

The military standoff in eastern Ladakh began in May 2020, and about 20 Indian soldiers were killed while defending the nation, and according to intelligence reports at the time estimated Chinese casualties at over 30. The standoff ended only in 2024 after both sides reached a deal.

"The US government is aware that China has conducted nuclear explosive tests, including preparing for tests with designated yields in the hundreds of tons. China has used decoupling to hide its activities from the world. China conducted one such yield-producing nuclear test on June 22, 2020," the US official tweeted.

Did China officially address the allegation?

On nuclear disarmament, China's ambassador Shen Jian has not denied or rejected DiNanno's remarks. 

He said that Beijing had “always acted prudently and responsibly on nuclear issues”.

"China notes that the US continues in its statement to hype up the so-called China nuclear threat. China firmly opposes such false narratives,” Shen said, adding, “It (the US) is the culprit for the aggravation of the arms race.”