A fresh nuclear controversy has erupted between the United States and China, overshadowing broader anxieties about the collapse of the global arms control architecture following theexpiration of the New START.
On February 6, Thomas G. DiNanno, US Under Secretary for Arms Control and International Security, alleged at the UN Conference on Disarmament that China conducted a “yield-producing” nuclear test on June 22, 2020, at the Lop Nur site. He stated that Beijing used “decoupling” techniques to reduce the detectability of seismic signals, suggesting deliberate concealment.
China swiftly rejected the claim. Chinese Foreign Ministry spokesperson Lin Jian described the accusation as political manipulation, arguing that Washington was distorting China’s nuclear policy to evade its owndisarmament responsibilities.
Located in China’s Xinjiang region, Lop Nur has historically served as Beijing’s primary nuclear test site. As per DiNanno’s remarks, the June 22, 2020 event involved a supercritical yield, implying a self-sustaining nuclear chain reaction rather than a subcritical experiment.
However, open-source verification efforts have yielded inconclusive results so far. According to a Center for Strategic and International Studies (CSIS) report, no visible optical indicators of a test in the northern tunnel areas were found between March and June 2020.
Seismological records present similar ambiguity. The Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) stated that its International Monitoring System did not detect any seismic event consistent with a nuclear explosion on June 22, 2020. Executive Secretary Robert Floyd said subsequent detailed analyses had not altered that conclusion.
Notably, the US Geological Survey did record a magnitude 4.1 seismic event that day. However, the epicentre was approximately 200 kilometres from Lop Nur, making a direct connection unlikely. This leaves the dispute in a grey zone — a claim by Washington unsupported by publicly available seismic data, yet not definitively disproven either.
At the heart of the allegations by the US lies the concept of “decoupling”. The technique involves detonating a device within a large underground cavity, such as a salt dome, to muffle seismic signatures. This makes the explosion appear significantly smaller.
The Cold War saw both the United States and the Soviet Union conducting decoupling experiments. The US Sterling test in Mississippi’s Tatum Salt Dome is one historical example. Lop Nur’s geological features — including salt lake formations — make it technically suitable for such experiments.
Yet verification thresholds remain contested. The CTBTO has indicated its system can reliably detect nuclear explosions of approximately 500 tonnes of TNT equivalent or higher. Analysts have noted that a test in the “few hundred tonne” range might evade detection under worst-case decoupling scenarios.
Source: India Latest News, Breaking News Today, Top News Headlines | Times Now
