DiNanno said the Chinese military had deliberately attempted to mask its activities, accusing the People’s Liberation Army of seeking to “conceal testing by obfuscating the nuclear explosions”.
He also alleged China used “decoupling” – a technique designed to weaken seismic signals – to obscure evidence of testing from international monitoring systems.
The allegations echo comments made in 2025 by Donald Trump, who suggested the US could resume nuclear testing “on an equal basis” with Russia and China. The US President did not specify what form that testing might take.
Shen Jian, China’s ambassador on disarmament, did not directly respond to the allegations but said Beijing had always acted prudently and responsibly on nuclear issues.
He accused Washington of exaggerating what he called a “so-called China nuclear threat”.
“China firmly opposes such false narratives,” he said. [The US] is the culprit for the aggravation of the arms race.”
Diplomats attending the Geneva conference told Reuters the US accusations were new and had raised concern among delegations.
The remarks were made as the US unveiled a proposal for new trilateral arms control talks involving Russia and China, following the expiration of the New START treaty – the last remaining nuclear arms agreement between Washington and Moscow – which lapsed on Friday.
Its expiration marks the first time in more than 50 years that the world’s two largest nuclear powers are operating without any binding limits on their strategic missiles and warheads.
DiNanno said the current framework no longer reflects global realities.
“Today, the United States faces threats from multiple nuclear powers,” he said. “In short, a bilateral treaty with only one nuclear power is simply inappropriate in 2026 and going forward.”
He also reiterated US projections that China will have over 1000 nuclear warheads by 2030.
China has rejected joining disarmament negotiations “at this stage”. Beijing has previously highlighted that it has a fraction of the other two nations’ warhead numbers – an estimated 600, compared with around 4000 each for Russia and the United States.
“In this new era we hope the US will abandon Cold War thinking... and embrace common and co-operative security,” Shen said.
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