The United States has disclosed fresh intelligence on an alleged Chinese nuclear test conducted in 2020, intensifying calls for Beijing and Moscow to commit to nuclear disarmament. Christopher Yeaw, the US Assistant Secretary of State for Arms Control and Non-Proliferation, presented declassified details to the UN-backed Conference on Disarmament in Geneva.

This revelation arrives amid heightened global tensions, following the expiry of the New START treaty between the US and Russia earlier this month. The pact's end removes constraints on the nuclear arsenals of the world's two largest nuclear powers, sparking fears of a renewed arms race.

Yeaw highlighted perceived flaws in New START, notably its failure to curb Russia's stockpile of up to 2,000 non-strategic nuclear warheads. More critically, he argued, the treaty overlooked China's rapid and opaque nuclear expansion.

US assessments indicate that China has aggressively grown its nuclear forces, potentially reaching parity with the US within four to five years. Yeaw described this build-up as deliberate and unconstrained, contrasting sharply with Beijing's public assurances of restraint.

Central to the US claims is a seismic event recorded on 22 June 2020 at China's Lop Nur test site in Xinjiang. Detected by an international monitoring station in Kazakhstan, the magnitude 2.75 tremor exhibited characteristics of a single-point explosion, distinct from earthquakes or mining blasts.

Yeaw noted China's efforts to hinder verification, including its refusal to permit seismic stations near Lop Nur at distances comparable to those allowed by the US at its Nevada test site. This opacity, he contended, undermines global non-proliferation efforts.

China vehemently denies the allegations. Ambassador Jian Shen dismissed them as baseless smears, accusing the US of fabricating pretexts to justify resuming its own nuclear tests. Beijing insists it upholds a voluntary moratorium on testing, consistent with commitments by the five recognised nuclear powers.

Shen countered that China's arsenal remains far smaller than those of the US or Russia, rendering trilateral arms control talks premature and inequitable. He emphasised differing strategic contexts, portraying US demands as unreasonable.

Independent analysts, such as Tong Zhao from the Carnegie Endowment, warn that confirmed Chinese yield-producing tests could erode Beijing's image as a responsible nuclear state. This might embolden US advocates for resuming tests to certify their ageing stockpile's reliability.

Recent US rhetoric has amplified these concerns. President Donald Trump signalled intentions to restart testing—dormant since 1992—though Energy Secretary Chris Wright clarified no explosive tests are planned. Yeaw referenced an "equal basis" response to peers' actions, implicitly targeting China and Russia.

Secretary of State Marco Rubio echoed this stance, affirming pursuits of multilateral disarmament while vowing not to tolerate unchecked expansions by adversaries. He cited estimates of China's warheads surging from around 200 in 2020 to over 600 today, projecting over 1,000 by 2030.

Yeaw urged the 65-nation Conference on Disarmament to press China and Russia towards transparency and engagement. The US has initiated bilateral talks, including with Russian delegates, and plans meetings with Chinese counterparts, alongside consultations with allies like France and Britain.

Trump's earlier push for a trilateral US-Russia-China pact faltered, but Washington now explores diverse formats—from bilateral to multilateral—to curb proliferation. Yeaw's address underscores a broader US strategy to multilateralise pressure on non-compliant nuclear states.

This episode highlights fracturing arms control architecture post-New START. With China's silo construction, hypersonic advancements, and sea-based deterrents accelerating, the US views Beijing's trajectory as destabilising. Moscow's tactical nuclear posture adds further complexity.

For India, observing from South Asia, these developments carry direct implications. As a nuclear triad possessor amid regional tensions with China, New Delhi monitors superpower dynamics closely. Enhanced US transparency could inform India's advocacy for a Fissile Material Cut-off Treaty at the Conference.

Beijing's denials align with its no-first-use doctrine and minimal deterrence claims, yet satellite imagery and SIPRI data corroborate arsenal growth. The Lop Nur event, if verified, would challenge China's CTBT adherence, potentially isolating it diplomatically.

Ultimately, Yeaw's disclosures aim to galvanise international consensus against unilateral buildups. Yet China's retort signals resistance, framing US actions as hypocritical amid its own modernisation. Reviving verifiable restraints will demand unprecedented concessions from all parties.

AP