US accuses China of secret nuclear tests

The United States accused Beijing on Friday of conducting a secret nuclear test in 2020 as it called for a new, broader arms control treaty that would bring in China as well as Russia.

The accusations at a global disarmament conference highlighted serious tensions between Washington and Beijing at a pivotal moment in nuclear arms control, a day after the treaty limiting US and Russian missile and warhead deployments expired.

"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," US Under Secretary of State for Arms Control and International Security Thomas DiNanno told a Disarmament Conference in Geneva.

The Chinese military "sought to conceal testing by obfuscating the nuclear explosions because it recognized these tests violate test ban commitments. China has used 'decoupling', a method to decrease the effectiveness of seismic monitoring, to hide their activities from the world," he said.

DiNanno said China had conducted one such "yield-producing test" on Jun 22, 2020.

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.

"It (the US) is the culprit for the aggravation of the arms race."

Diplomats at the conference said the US allegations were new and concerning.

GLOBAL ARMS CONTROL FACES A CRITICAL MOMENT

The 2010 New START treaty which ran out on Thursday left Russia and the United States for the first time in more than half a century without any binding constraints on their deployments of strategic missiles and warheads.

US President Donald Trump wants to replace it with a new agreement including China, which is rapidly increasing its own arsenal.

DiNanno told the Geneva conference: "Today, the United States faces threats from multiple nuclear powers. In short, a bilateral treaty with only one nuclear power is simply inappropriate in 2026 and going forward."

He reiterated US projections that China will have over 1,000 nuclear warheads by 2030.

But Shen, the Chinese delegate, reiterated that his country would not participate in new negotiations at this stage with Moscow and Washington. Beijing has previously highlighted that it has a fraction of their warhead numbers - an estimated 600, compared to around 4,000 each for Russia and the US

"In this new era we hope the US will abandon Cold War thinking... and embrace common and cooperative security," Shen said.