China Conducted Secret Nuclear Test Days After Galwan Clash In 2020: US

Last Updated:February 08, 2026, 07:17 IST

US Under Secretary of State Thomas G DiNanno said China conducted one such yield-producing nuclear test on June 22, 2020.

US Under Secretary of State Thomas G DiNanno has claimed that China carried out secret nuclear explosive tests days after India-China Galwan conflict. He said China conducted one such yield-producing nuclear test on June 22, 2020 while the Galwan skirmish started on June 15, 2020.

The date cited by the US official comes a week after the India-China Galwan conflict, when 20 Indian soldiers were killed in action while defending the nation. Intelligence reports had said over 30 Chinese soldiers were also killed.

“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," read DiNanno’s post on X.

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

DiNanno also said that Beijing used methods designed to reduce the effectiveness of seismic monitoring.

What is the ‘decoupling’ technique used by China?

In a post on X, DiNanno said China used “decoupling", a method meant to weaken seismic monitoring, to conceal its activities.

“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," he wrote.

DiNanno said there is a need for a new nuclear architecture that addresses present threats rather than older treaty structures.

He referred to the Strategic Arms Reduction Treaty (New START), signed in 2010, saying its limits on warheads and launchers were no longer relevant in 2026.

What US expert said on New START And China?

The US official said almost all US deployed nuclear forces were covered by New START, while only a fraction of Russia’s larger stockpile was covered. He added that no Chinese nuclear weapons were covered under the treaty.

He said China was no longer constrained by the political-military circumstances of 2010 and that the US could now take steps to strengthen deterrence for itself and its allies.

Trump’s earlier statement

US President Donald Trump had hinted at similar accusations on October 31 last year, saying Washington would begin nuclear testing “on an equal basis" with Moscow and Beijing, without giving details.

DiNanno’s remarks came as he presented a US plan calling for three-way nuclear talks with Russia and China after the expiry of New START on Thursday.

China has already rejected joining disarmament negotiations “at this stage".

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