Thomas DiNanno, who is the US Under Secretary of State for Arms Control and International Security, accused China of conducting secret nuclear tests. He made the claim during a speech at the Conference on Disarmament in Geneva on Friday.
DiNanno stated, “Today, 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.” This occurred one day after the New START treaty expired.
Details of the Claim Emerge
DiNanno specified that China carried out a yield-producing nuclear test on June 22, 2020. He explained, “China conducted one such yield-producing nuclear test on June 22 of 2020.”
Additionally, he alleged that China used decoupling methods to evade seismic monitoring and conceal the explosions. The Trump administration linked these actions to violations of international test ban commitments.
Administration Pushes for New Treaty
The US called for a broader nuclear arms control agreement. DiNanno emphasized the need for a multilateral deal involving China and Russia. He noted, “A bilateral treaty with only one nuclear power is simply inappropriate in 2026 and going forward.” This push followed President Donald Trump’s earlier order in October 2025 to resume US nuclear testing.
Shen Jian, who is China’s ambassador to the Conference on Disarmament, rejected the claims. He stated, “The US continues in its statement to hype up the so called China nuclear threat. China firmly opposes such false narratives.” Jian added that the US acted as the culprit in aggravating the arms race. China refused to join trilateral negotiations at that stage.
Background of Escalating Tensions
The New START treaty limited US and Russian strategic warheads to 1,550 each. Its expiration left no constraints on the world’s largest nuclear arsenals. Trump previously accused China and Russia of secret tests in 2025, which both denied.
Global Implications Highlighted
These developments raised fears of a new arms race. Stakeholders anticipated further diplomatic exchanges as nations navigated the post treaty landscape. The conference underscored divisions among nuclear powers.
