US accuses China of secret nuclear explosive testing, pushes for new arms control treaty

The U.S. on Friday accused China of conducting a secret nuclear explosive test, while pushing for a new arms control treaty.

"I can reveal that the U.S. government is aware that China has conducted nuclear explosive tests, including preparing for tests with designated yields in the hundreds of tons," U.S. Under Secretary of State for Arms Control and International Security Thomas DiNanno told a Disarmament Conference in Geneva, Reuters reported.

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," DiNanno said.

He added that, in June 2020, China had conducted one such "yield-producing test."

Shen Jian, China's ambassador on disarmament, did not directly address DiNanno's claim, but said his country had always acted prudently and responsibly on nuclear issues.

"China notes that the U.S. continues in its statement to hype up the so-called China nuclear threat. China firmly opposes such false narratives," Shen said. The U.S. "is the culprit for the aggravation of the arms race."

The 2010 New START treaty ended on Thursday, which is the first time in more than 50 years that Russia and the U.S. do not have any binding constraints on their deployments of strategic missiles and warheads.

President Trump wants to replace the treaty with a new agreement that includes China, which is quickly increasing its own nuclear arsenal.

"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," DiNanno said.

He added that the U.S. projects that China will have over 1,000 nuclear warheads by 2030.

However, Shen said that China would not participate in new negotiations at this stage with Russia and the U.S.

China has previously noted that it has a fraction of those countries' warhead numbers at an estimated 600, compared to around 4,000 each for Russia and the U.S.

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