Washington: The United States has revealed new details about what it believes was a covert underground nuclear test conducted by China in June 2020, intensifying tensions between the two powers and raising fresh concerns about global nuclear monitoring and arms control.
A senior US official said the suspected test took place at China’s Lop Nor nuclear test site in the remote Xinjiang region. According to the official, seismic sensors in Kazakhstan recorded a magnitude 2.75 event on the same day, a signal that US analysts say is consistent with an underground explosion rather than an earthquake or mining activity.
China has strongly denied the allegation, describing it as politically motivated and without basis. Beijing maintains that it respects its international commitments and rejects claims that it conducted any nuclear test.
Data from the Comprehensive Nuclear Test Ban Treaty Organization detected two small seismic events on the day in question, but the agency said the signals were too weak to confirm whether a nuclear explosion occurred. Independent experts note that such low level seismic data cannot conclusively determine the nature of the event.
US officials have suggested that if a test occurred, China may have used a method known as decoupling. This technique involves detonating a device inside a large underground cavity to reduce seismic signals and make detection more difficult. Specialists say verifying the use of such a method is extremely challenging.
The allegations come at a time of growing strategic competition and concern about nuclear weapons expansion. US defense assessments indicate that China is rapidly increasing its nuclear arsenal and could possess more than 1,000 warheads by 2030.
Washington has been urging Beijing to join future nuclear arms control negotiations, especially as existing agreements face uncertainty. The dispute also comes amid debate in the United States over whether it should reconsider its long standing moratorium on nuclear testing, a move critics warn could trigger a renewed global arms race.
Both the United States and China have signed the Comprehensive Nuclear Test Ban Treaty but have not ratified it, leaving the treaty without full legal force while maintaining strong international expectations against nuclear testing.
Analysts say the dispute highlights the growing difficulty of verifying very small nuclear tests and the rising mistrust between major powers. The issue could further complicate efforts to strengthen global nuclear restraint and prevent a new era of weapons testing.