Overview
- Assistant Secretary Christopher Yeaw said a Kazakhstan station (PS23) registered a magnitude‑2.75 signal on June 22, 2020, about 450 miles from China’s Lop Nur site, calling it very likely a singular explosion not consistent with quakes or mining.
- U.S. officials allege China used decoupling in a large underground cavity to muffle seismic waves and have cited preparations for tests with designated yields in the hundreds of tons.
- CTBTO chief Robert Floyd said PS23 recorded two very small events 12 seconds apart that fell far below the system’s roughly 500‑ton TNT detection threshold, so the cause cannot be assessed with confidence.
- China has rejected the allegation as unfounded political manipulation, and the Kremlin has also denied that China or Russia conducted secret nuclear tests.
- Washington signals readiness to conduct low‑yield tests on an “equal basis,” with no timing announced, as debate intensifies following New START’s Feb. 5 expiration and experts note the evidence remains limited and potentially consistent with non‑nuclear causes.