US challenges China over alleged secret nuclear tests and arsenal expansion

The United States is engaging in confidential diplomatic talks with China regarding allegations of covert low-yield nuclear testing and a rapid expansion of China’s strategic nuclear arsenal. US officials have raised concerns over potential violations of the 1996 Comprehensive Nuclear-Test-Ban Treaty, specifically targeting the Lop Nur facility in northwest China. In February 2026, the US formally accused China of conducting a secret yield-producing nuclear test in June 2020 by utilizing underground “decoupling” techniques to evade seismic detection.

Satellite intelligence has identified extensive infrastructure upgrades across at least seven Chinese sites, including facilities in Pingtong, Zitong, Jiuquan, Jinta, Guangyuan, and Mianyang. While China’s Mianyang laser complex allows for advanced thermonuclear modeling through laser fusion—a practice permitted under current rules—the parallel buildup of physical infrastructure supports an arsenal that has already exceeded 600 warheads and is projected to reach 1,500 by 2035.

This standoff has triggered a domestic debate in the United States regarding the potential end of its decades-long nuclear test moratorium. President Donald Trump has indicated that the US may resume nuclear testing on an “equal basis” if these alleged breaches continue. In response, the US is seeking enhanced verification measures, including improved seismic and radiological detection capabilities.