US accuses China of underground nuclear tests – this is what we know

Authored by inews.co.uk and submitted by theipaper
image for US accuses China of underground nuclear tests – this is what we know

The extraordinary claim, if true, would mark the first nuclear test of the 21st century by any country other than North Korea

cancel email WhatsApp link share Share bookmark Save

share cancel email WhatsApp link bookmark

The US has accused China of conducting secret nuclear weapons tests and risking a new nuclear arms race.

“Today, 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,” said Thomas DiNanno, undersecretary of state for arms control and international security, at a conference in Geneva on Friday.

DiNanno accused Beijing of masking the alleged tests with “a method to decrease the effectiveness of seismic monitoring to hide their activities from the world”. One such test took place on 22 June, 2020, he said, without providing evidence.

New Feature In Short Quick Stories. Same trusted journalism.

The claims follow the expiration of New START this week, the main agreement governing nuclear proliferation between the US and Russia, which hold the world’s largest stockpiles of nuclear weapons.

DiNanno said that China’s alleged clandestine nuclear activity proved that previous agreements were inadequate and called for a “new architecture that addresses the threats of today, not those of a bygone era”.

He called on fellow nuclear powers to take urgent action to prevent an “unmitigated nuclear arms race”.

The extraordinary claim, if true, would mark the first nuclear test of the 21st century by any country other than North Korea. The US, China, and Russia have all pledged not conduct nuclear tests.

China’s ambassador on disarmament, Shen Jian, did not directly address DiNanno’s charge, but said 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,” he said.

Donald Trump said last October that the US would resume nuclear tests on an “equal basis” with China and Russia, accusing the rival powers of conducting tests. Beijing and Moscow denied this.

Arms control researchers believe China is rapidly expanding its nuclear arsenal of an estimated 600 warheads. The Stockholm International Peace Research Institute (Sipri)’s latest report stated: “China’s nuclear arsenal is growing faster than any other country’s, by about 100 new warheads a year since 2023.”

China displays the DF-31BJ land-based intercontinental missiles during a military parade in Beijing last September (Photo: VCG/Getty)

DiNanno said on Friday that China was on course to have “1,000 nuclear warheads by 2030, and Russia is supporting this buildup by helping China develop the weapons-grade fissile material necessary for its expansion”.

US researchers reported last year that all three of the leading nuclear powers were preparing nuclear test sites based on satellite imagery.

Andrey Baklitskiy, senior researcher at the WMD programme of the UN Institute for Disarmament Research (UNIDIR), said the US claims raised urgent questions.

“The US statement accused China of using a decoupling technique – having [an] explosion happen in an underground cavity to reduce detection of the seismic signal – in this way the test may look much weaker and similar to a conventional explosion. We don’t know anything else about how the US made this determination and how they were able to determine this was not a conventional explosion in the first place,” he said.

The Comprehensive Nuclear-Test-Ban Treaty Organisation (CBTBO), a body tasked with monitoring for nuclear tests, said it had not detected activity consistent with the US claim.

“Regarding reports of possible nuclear tests with yields in the hundreds of tonnes, on 22 June 2020, the CTBTO’s (systems) did not detect any event consistent with the characteristics of a nuclear weapon test explosion at that time. Subsequent, more detailed analyses have not altered that determination,” a spokesperson said.

“Any nuclear test explosion, by any state, is of deepest concern.”

But Dr David Albright, a leading nuclear weapons specialist and founder of the US-based Institute for Science and International Security, which monitors nuclear test sites around the world, said the allegations against China were plausible.

“We monitor activity at the Chinese test sites and there has been activity,” he told The i Paper, adding that activity was detected on the date cited by DiNanno.

“These are very low yield tests rather than full-scale nuclear tests,” said Dr Albright, but added that the scale could be obscured by the practice of “decoupling” to dampen seismic signals.

Prospects of a new nuclear agreement appeared slim, the physicist said, while the US perceives China to be resisting transparency and rapidly expanding its arsenal, and Russia continues to deploy new nuclear-capable systems – such as hypersonic missiles used in Ukraine.

“The US wants to have a nuclear arsenal that can counter both China and Russia. And right now we have one to counter Russia. And so there will be a build up in the numbers of weapons on the US side,” he said. “We are engaged in a kind of arms race now.”

Sea_Outside162 on February 6th, 2026 at 18:43 UTC »

Guarantee trump is setting off a nuclear bomb .. the most incompetent administration ever has the keys the codes and the desire to make go boom , damned be the consequences cuz he is already on his way out, and his ascendance doomed

Outside-Storage-1523 on February 6th, 2026 at 17:27 UTC »

OK so US is going to do its own and want to place the blame first, "hey we didn't do it first".

theipaper on February 6th, 2026 at 17:02 UTC »

The US has accused China of conducting secret nuclear weapons tests and risking a new nuclear arms race.

“Today, 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,” said Thomas DiNanno, undersecretary of state for arms control and international security, at a conference in Geneva on Friday.

DiNanno accused Beijing of masking the alleged tests with “a method to decrease the effectiveness of seismic monitoring to hide their activities from the world”. One such test took place on 22 June, 2020, he said, without providing evidence.

The claims follow the expiration of New START this week, the main agreement governing nuclear proliferation between the US and Russia, which hold the world’s largest stockpiles of nuclear weapons.

DiNanno said that China’s alleged clandestine nuclear activity proved that previous agreements were inadequate and called for a “new architecture that addresses the threats of today, not those of a bygone era”.

He called on fellow nuclear powers to take urgent action to prevent an “unmitigated nuclear arms race”.

The extraordinary claim, if true, would mark the first nuclear test of the 21st century by any country other than North Korea. The US, China, and Russia have all pledged not conduct nuclear tests.

China’s ambassador on disarmament, Shen Jian, did not directly address DiNanno’s charge, but said 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,” he said.

Donald Trump said last October that the US would resume nuclear tests on an “equal basis” with China and Russia, accusing the rival powers of conducting tests. Beijing and Moscow denied this.

Arms control researchers believe China is rapidly expanding its nuclear arsenal of an estimated 600 warheads. The Stockholm International Peace Research Institute (Sipri)’s latest report stated: “China’s nuclear arsenal is growing faster than any other country’s, by about 100 new warheads a year since 2023.”