US Says Nuclear Tests by China, Russia Compel It to Act

The US has shaken a disarmament conference by charging that China carried out at least one clandestine nuclear explosive test—on June 22, 2020—and is preparing others with yields in the "hundreds of tons." China answered that the Americans are looking for cover to resume their own nuclear testing, NPR reports. The countries have observed a now-unraveling, decades-long moratorium under the Comprehensive Nuclear-Test-Ban Treaty, which they've signed but not ratified. Thomas DiNanno, US undersecretary of state for arms control, said in a speech Friday that recent secretive underground tests conducted by China and Russia make the US justified in taking "parallel steps," per the Washington Post.

China's Foreign Ministry called the accusations "outright lies," though its envoy to the talks, Shen Jian, avoided giving a direct answer, per the Wall Street Journal. The evidence is murky. Global monitoring systems and independent analysts cited by NPR said they've seen no seismic signal consistent with a sizable nuclear blast at China's test site, though US officials suggest China could be using "decoupling" techniques to muffle evidence underground.

Experts said that any Chinese tests in the range that US officials describe could be aimed either at improving weapon safety or developing new, smaller warheads—against the backdrop of China's rapidly growing arsenal and fading global taboos on testing. President Trump announced last fall that the US would resume testing nuclear weapons testing because of other countries' activities.