United States Details Claim of Secret Chinese Nuclear Test in 2020

U.S. Alleges Covert Nuclear Detonation by China

The United States has offered additional specifics concerning its claim that China carried out a clandestine nuclear weapons test in 2020. Top administration officials have presented what they describe as new intelligence to support the contested assertion, which Beijing has firmly rejected. The allegations come amidst a broader debate on nuclear arms control and the future of international testing moratoriums.

Details of the Allegation

According to Christopher Yeaw, Assistant Secretary of State for Arms Control and Nonproliferation, the alleged event occurred on June 22, 2020, in the vicinity of Lop Nur, China's main nuclear test site in the western Xinjiang region. The U.S. claims that seismic data, recorded by a remote station in Kazakhstan, detected an activity measuring between 2.75 and 2.76 magnitude. Yeaw stated that this activity was inconsistent with natural earthquakes or mining explosions, suggesting it was a 'singular explosion' consistent with a nuclear test.

Thomas DiNanno, Undersecretary of State for Arms Control and International Security, previously disclosed that the U.S. government was aware of China conducting 'yield-producing nuclear tests,' including preparations for tests with 'designated yields in the hundreds of tons.' Both officials accused China of employing 'decoupling' techniques—detonating devices deep underground to muffle the blast and reduce the effectiveness of seismic monitoring systems—to conceal these activities.

China's Rebuttal and International Scrutiny

China has vehemently denied the U.S. accusations. The Chinese Foreign Ministry has labeled the claims as 'outright lies' and 'completely groundless,' asserting that Washington is fabricating pretexts to justify resuming its own nuclear testing program. China maintains that it adheres to a voluntary moratorium on nuclear explosive testing and upholds a self-defensive nuclear strategy.

The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), responsible for monitoring nuclear tests globally, stated that its International Monitoring System did not detect any event consistent with the characteristics of a nuclear weapon test explosion on June 22, 2020. Independent experts have also expressed skepticism, noting that while seismic wave ratios might be consistent with an explosion, the signal was weak and recorded at a single station, making conclusive evidence difficult.

Both the United States and China are signatories to the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which prohibits all nuclear weapon test explosions. However, neither country has ratified the treaty, meaning it has not officially entered into force.

Broader Implications for Arms Control

The U.S. allegations surface shortly after the expiration of the New START Treaty, the last remaining nuclear arms control agreement between the United States and Russia. The Trump administration has advocated for a new trilateral arms control agreement that would include China and Russia. U.S. officials have indicated that the alleged Chinese test could serve as a catalyst for the United States to resume its own nuclear testing on an 'equal basis,' though not at the scale of past atmospheric tests.