The United States government has accused China of conducting secret nuclear explosive tests, including preparations for large-scale detonations, according to US Under Secretary of State for Arms Control Thomas DiNanno. Speaking at the United Nations Conference on Disarmament in Geneva on 6/2, DiNanno stated that these tests involved destructive power equivalent to hundreds of tons of explosives.

He further alleged that China carried out one such nuclear test on 22/6/2020.

A DF-5C intercontinental ballistic missile at a parade in Tiananmen Square, Beijing, in 9/2025. Photo: AFP.

DiNanno asserted the Chinese military "sought to conceal the testing process," recognizing these actions violated test ban commitments. He further indicated that China employed techniques to diminish the effectiveness of seismic monitoring during these operations.

Chinese officials have yet to comment on these allegations.

DiNanno's remarks accompanied his presentation of a plan for trilateral negotiations with Russia and China, aiming to establish new nuclear weapons limits. This initiative follows the expiration of the New Strategic Arms Reduction Treaty (New START) on 5/2, which was the last remaining nuclear arms control agreement between the US and Russia.

Beijing has consistently declined to engage in nuclear arms control treaties with Washington and Moscow. Its rationale stems from the comparatively smaller size of its warhead arsenal next to those of the other two nuclear powers.

Former US President Donald Trump leveled similar accusations late last year, though without the specific details provided by Under Secretary DiNanno. In late 10/2025, Trump announced the US would commence nuclear weapons testing on a proportional basis with Russia and China, but did not elaborate on the nature of the tests he intended to revive.

Reporting by Vu Hoang, with AFP.