China Conducted Covert Nuclear Test Days After 2020 Galwan Clash: US

The United States has accused China of conducting a covert, low-yield nuclear test on June 22, 2020, shortly after the Galwan Valley clash with India. US officials claim China used a “decoupling” technique to hide the explosion’s seismic signals.

The United States has accused China of carrying out a covert nuclear explosive test on June 22, 2020—just a week after the deadly Galwan Valley clash between Indian and Chinese troops in eastern Ladakh.

The allegation was made public by Thomas G. DiNanno, the US Under Secretary of State for Arms Control and International Security, during a Disarmament Conference in Geneva, drawing renewed attention to global nuclear stability and arms control norms in a rapidly shifting geopolitical environment.

According to the US accusation, the suspected test was “yield-producing”, involving explosive yields in the hundreds of tons, and Beijing allegedly used a technique called “decoupling” to mask the seismic signals that would normally indicate an underground nuclear test. This method, if true, would have made it harder for international monitoring systems to detect the explosion, raising concerns about transparency and compliance with nuclear test ban commitments.

The alleged nuclear test’s timing—occurring days after the June 15, 2020, Galwan clash, where 20 Indian soldiers were killed and Indian intelligence assessments suggest substantial Chinese casualties—adds a strategic dimension to the US claim, although Washington stopped short of directly linking the events.

The accusation comes at a critical moment for global arms control. The New START treaty, the last remaining binding nuclear arms control agreement between the United States and Russia, recently expired, leaving no formal limitations on strategic nuclear deployments for the first time since the early Cold War era. US officials argue that this development highlights the need for a new nuclear architecture that includes not just Russia but also China, which is rapidly expanding its own arsenal and is not covered by New START constraints.

Beijing has denied any such testing and accused Washington of exaggerating threats and spreading “false narratives,” emphasising its conventional commitment to a nuclear testing moratorium and no-first-use policy. China’s ambassador for disarmament stated that such allegations are politically motivated and distort the country’s defence posture, an assertion that reflects the broader mistrust between the nuclear powers

This intensifying dispute has broader implications for global non-proliferation efforts and regional security dynamics. The US push for a three-party arms control framework involving the US, Russia, and China underscores Washington’s view that existing treaties failed to reflect the realities of the modern multipolar nuclear landscape. Critics warn that without new constraints and transparency mechanisms, mistrust and worst-case assumptions could fuel an arms race among major powers.

The allegations have also stirred geopolitical sensitivities in Asia, particularly for India, which continues to manage border tensions with China while navigating broader strategic alignments. Whether the US claims can be independently verified remains a significant question, as global monitoring bodies have not publicly confirmed definitive evidence of any Chinese nuclear detonation in 2020.