Overview
- US Under Secretary Thomas DiNanno alleged at the Conference on Disarmament that China conducted a low‑yield underground nuclear explosive test at Lop Nur on June 22, 2020 using decoupling to muffle seismic signals.
- China rejected the accusation as completely groundless, with spokesperson Lin Jian and envoy Li Song accusing Washington of political manipulation and reaffirming China’s moratorium and support for the CTBT.
- CTBTO Executive Secretary Robert Floyd said the International Monitoring System detected no event consistent with a nuclear weapon test at the time cited by the US.
- The allegation surfaced days after New START expired, as Washington presses for a broader arms‑control framework that includes China and recalibrates its nuclear posture.
- Arms‑control experts warn that making public claims without shared, verifiable evidence—alongside US preparations for possible testing ordered in late 2025—could erode the testing taboo and deepen mistrust.