U.S. Officials Claim China Conducted Secret Nuclear Test in 2020

A senior U.S. official has revealed new details about what American intelligence believes was a covert Chinese nuclear test conducted at the Lop Nur test grounds in June 2020, potentially signaling a concerning shift in global nuclear testing norms.

Speaking at a Hudson Institute event in Washington, D.C. on Tuesday, Assistant Secretary of State Christopher Yeaw stated that a seismic station in Kazakhstan detected a magnitude 2.75 explosion at China’s nuclear testing site 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 explained. He dismissed alternative explanations, noting the data was “not consistent with mining detonations” and “entirely not consistent with an earthquake.”

The U.S. allegation represents a significant diplomatic challenge, as it would mark the first known nuclear test by a major power since North Korea’s series of tests that concluded in 2017. The Comprehensive Nuclear-Test-Ban Treaty, while never formally entering into force, has established a de facto international norm against nuclear testing that has largely held since the 1990s.

Thomas DiNanno, undersecretary of state for arms control and international security, expanded on these claims at the United Nations Conference on Disarmament, stating that China may be preparing for larger tests. “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.

DiNanno further alleged that Beijing employs “decoupling” techniques—methods to dampen seismic signals from nuclear detonations—to “hide its activities from the world.”

The Chinese government has categorically rejected these allegations. Liu Pengyu, a spokesperson for China’s embassy in Washington, told NBC News that the U.S. report constitutes “political manipulation” and accused the United States of “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,” Liu added.

These accusations emerge against the backdrop of China’s rapid military modernization and nuclear arsenal expansion. Defense analysts have noted that China is engaged in the fastest buildup of nuclear weapons in its history, with satellite imagery showing extensive construction of new missile silos in western China.

The allegations have significant implications for global nuclear security. If confirmed, a Chinese test would undermine decades of international efforts to maintain a moratorium on nuclear testing. It could potentially trigger a new era of nuclear competition, as both Russia and the United States might reconsider their own testing policies.

The controversy has also reignited debate in Washington about the U.S. approach to nuclear deterrence. Since 1992, the United States has maintained its nuclear arsenal through the Stockpile Stewardship Program, which relies on computer simulations and non-nuclear experiments rather than actual detonations. Some defense analysts question whether this approach remains adequate in an era of renewed great-power nuclear competition.

The timing of this revelation is particularly sensitive, coming amid already heightened U.S.-China tensions across multiple domains including trade, technology, human rights, and territorial disputes in the South China Sea and Taiwan Strait.

Arms control experts note that verification of such claims is inherently difficult. The Comprehensive Nuclear-Test-Ban Treaty Organization maintains a global network of monitoring stations designed to detect nuclear tests, but low-yield tests conducted with decoupling techniques can be challenging to identify conclusively.

As both nations continue to modernize their nuclear forces, the allegations underscore the urgent need for renewed dialogue on nuclear arms control and risk reduction between the world’s major nuclear powers.