New Delhi/Washington: The United States has claimed that China carried out a covert nuclear explosive test in June 2020, days after the deadly Galwan Valley confrontation between Indian and Chinese troops, triggering renewed concerns over Beijing’s nuclear ambitions and transparency.
Allegation Tied to a Sensitive Moment
According to US Deputy Under Secretary Thomas G. DiNanno, Chinese authorities conducted the underground test on June 22, 2020—exactly a week after the June 15 Galwan clash in which 20 Indian soldiers were killed. The American official alleged that Beijing employed a specialised method known as “decoupling” to dampen seismic signals, allowing the blast to evade global monitoring systems.
DiNanno made the claims through public remarks and social media posts, asserting that China has engaged in “nuclear explosive testing activities,” including preparations for experiments involving yields of several hundred tons. He said the decoupling technique enables underground detonations to appear significantly smaller on seismic sensors, making detection by international networks more difficult.
The Galwan incident marked the most serious military confrontation between India and China in decades, sharply escalating tensions along the Line of Actual Control (LAC). While Beijing has never disclosed its casualties, both sides acknowledged losses, and the standoff reshaped regional security dynamics.
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The ‘Decoupling’ Technique and Detection Gaps
The US official argued that the alleged test underscores the urgent need for a revamped global nuclear framework suited to contemporary threats rather than Cold War-era realities. He warned that traditional arms control arrangements are rapidly losing relevance at a time when certain nuclear powers are expanding their arsenals at an unprecedented pace.
DiNanno also referred to the New START treaty, signed in 2010 to cap deployed strategic nuclear weapons held by the United States and Russia. Set to expire in 2026, the agreement limits warheads and launch systems but, according to Washington, no longer reflects current geopolitical realities.
He noted that nearly all deployed US nuclear forces fall under New START constraints, while only a fraction of Russia’s stockpile is covered. China, meanwhile, is not bound by the treaty at all, a gap that American officials say has contributed to growing strategic imbalance.
Galwan, Nuclear Expansion and Regional Stakes
Washington has repeatedly accused Beijing of rapidly modernising and expanding its nuclear programme while keeping much of it shielded from international scrutiny. Security experts believe this trajectory could further destabilise the Indo-Pacific, particularly amid already heightened tensions over Taiwan and the South China Sea.
For India, the allegation carries added significance given the sustained military buildup along the LAC since 2020. Defence analysts say that if the US claims are substantiated, they would signal a major shift in China’s strategic posture, with direct implications for regional deterrence and India’s security calculus.
China has previously dismissed similar accusations, insisting it adheres to a responsible nuclear policy and respects the spirit of test-ban agreements. Beijing has yet to issue an official response to the latest US assertions.
Strain on an Aging Global Nuclear Framework
International affairs specialists expect the issue to feature prominently at the United Nations and other multilateral forums in the coming months. The United States has already urged allied nations to strengthen cooperation on nuclear monitoring and arms control mechanisms.
Analysts caution that allegations of post-Galwan nuclear testing go beyond technical compliance debates. They touch the core of Asia’s evolving security architecture and could further strain already fragile India–China relations, even as global powers grapple with reshaping deterrence frameworks for a more volatile era.
