Washington wants Beijing to join a new nuclear arms deal after the New START treaty between the US and Russia expires.
Published on February 7, 2026
An international monitor said it has seen no evidence to support claims by a senior United States official accusing China of conducting secret nuclear tests in 2020 and concealing activities that violate nuclear test ban treaties.
US Secretary of Arms Control and International Security Thomas DiNano made the assertion about China on Friday at the United Nations Conference on Disarmament in Geneva, Switzerland. Nuclear deal with Russia expires.
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“I can disclose that the US government is aware that China has conducted nuclear explosive tests with hundreds of tons of designated products in preparation for the tests,” DiNano said at the conference.
China’s military “tried to cover up the test by obfuscating the nuclear explosions because they recognized that the tests violated their test ban commitments,” he said.
“China conducted a similar nuclear test on June 22, 2020,” he said.
DiNano also made his accusations in a series of posts on social media and made the case for a “new architecture” in the nuclear arms control treaty. Termination of the New START Treaty with Russia this week.
“New START was signed in 2010, and limits on warheads and launchers are irrelevant in 2026 when one nuclear power is expanding its arsenal at a rate and pace not seen in half a century and the other continues to maintain and develop a vast array of nuclear systems not controlled by the terms of New START,” he said.
Robert Floyd, executive secretary of the Comprehensive Nuclear-Test-Ban Treaty Organization, said in a statement on Friday that the body’s monitoring system “did not detect any event consistent with the characteristics of a nuclear test explosion” during the alleged Chinese test, adding that the assessment had not changed after the details.
Shen Jian, China’s ambassador on nuclear disarmament, did not directly address Dinanno’s accusation at the conference but said Beijing has always acted prudently and responsibly on nuclear issues while the US “continues to distort and discredit China’s national defense capabilities in its statements”.
“We strongly oppose this false narrative and reject the US’s baseless accusations,” Shen said.
“In fact, the US’s series of negative actions in the area of nuclear arms control is the biggest threat to international security,” he said.
Later on social media, Shen said, “China has always respected its commitment to moratorium on nuclear testing”.
Diplomats at the conference said the US allegations were new and relevant.
China, like the US, has signed but not ratified the Comprehensive Nuclear Test Ban Treaty (CTBT), which bans explosive nuclear tests. Russia signed and ratified it, but withdrew its ratification in 2023.
US President Donald Trump has previously directed the US military to be ready to resume nuclear tests, saying other countries are doing so, without giving details.
The US president said on October 31 that Washington would begin testing nuclear weapons “on an equal basis” with Moscow and Beijing, but without clarifying what type of nuclear testing he wants to resume.
He has also said he wants China to participate in any future nuclear deal, but officials in Beijing have shown little interest in his proposal.