Mysterious 2020 explosion in China had hallmarks of nuclear test, US official alleges

Assistant Secretary of State Christopher Yeaw spoke at a Hudson Institute event in Washington, D.C., on Tuesday, and said evidence of the explosion came from a seismic station in Kazakhstan. The station detected a magnitude 2.75 explosion located at China's Lop Nur test grounds on June 22, 2020.

"I've looked at additional data since then. There is very little possibility I would say that it is anything but an explosion, a singular explosion," Yeaw said, adding that data was not consistent with mining detonations.

"It's also entirely not consistent with an earthquake," he added. "It is... what you would expect with a nuclear explosive test."

China's embassy in Washington has rejected the Trump administration's claim, telling NBC News that the report is "political manipulation," and the U.S. is "evading its own nuclear disarmament responsibilities."

"China urges the U.S. to reaffirm the five nuclear-weapon states' commitment on refraining from nuclear tests, uphold the global consensus against nuclear tests, and take concrete steps to safeguard the international nuclear disarmament and non-proliferation regime," spokesperson Liu Pengyu told the outlet.

U.S. officials warned that Beijing may be preparing tests in the "hundreds of tons" range - a scale that underscores China's accelerating nuclear modernization and complicates efforts to draw Beijing into arms control talks.

"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," DiNanno said during remarks at the United Nations Conference on Disarmament.

He added, "China conducted one such yield-producing nuclear test on June 22 of 2020."

DiNanno also accused Beijing of using "decoupling" - detonating devices in ways that dampen seismic signals - to "hide its activities from the world."

The accusation has sharpened questions about verification, deterrence and whether the U.S. stockpile stewardship program - which relies on advanced simulations rather than live detonations - remains sufficient in an era of renewed great-power nuclear competition.