A top U.S. State Department official accused China on Monday of massively expanding its nuclear arsenal without transparency, warning it could reach parity with the United States and Russia in four or five years.

Christopher Yeaw, assistant secretary for arms control and nonproliferation, made the remarks at the Conference on Disarmament in Geneva. He stated that China has "deliberately, and without constraint, massively expanded its nuclear arsenal without transparency or any indication of China’s intent or end point." Yeaw noted the buildup is unprecedented, deliberate, rapid, and opaque, despite Beijing's recent white paper offering no endpoint.

U.S. assessments indicate China's nuclear stockpile stood at around 200 warheads when the New START treaty was signed in 2010. The Pentagon's 2025 report to Congress estimated it reached the low 600s by late 2024, with the People's Liberation Army on track to exceed 1,000 operational warheads by 2030. Yeaw said Beijing is poised to possess fissile material for more than 1,000 warheads by that year, aided by Russian transfers of highly enriched uranium fuel for China's CFR-600 reactors.

Yeaw also reiterated U.S. intelligence claims of a covert Chinese nuclear test on June 22, 2020, at the Lop Nur site. Seismic data from Kazakhstan detected a magnitude 2.75 event consistent with a 10-ton nuclear explosion, or five tons of conventional explosive equivalent. He accused China of using techniques to conceal such activities and obstructing international monitoring.

The accusations came days after New START, the U.S.-Russia treaty limiting deployed strategic warheads to 1,550 each, expired on February 5. Washington claims Russia violated the pact from 2022 and exceeded limits, while ignoring its nonstrategic arsenal of up to 2,000 warheads and novel systems. Yeaw described the expiration as an opportunity for multilateral arms control, including China, to prevent a new race.

China rejected the claims. Ambassador Shen Jian called them groundless smears of its nuclear policy and insisted Beijing would not engage in an arms race. He argued China's arsenal is not comparable to those of the U.S. and Russia, each with over 5,000 warheads, making trilateral talks unfair. Foreign Ministry spokesperson Mao Ning said the U.S. allegations of tests are unsubstantiated, reaffirming China's support for the Comprehensive Nuclear-Test-Ban Treaty moratorium.

The U.S. has pushed for Beijing's inclusion in talks since earlier statements this month. Under Secretary Thomas DiNanno, on February 6, highlighted China's denial of silo fields discovered post-2021 and Russian fissile material support. President Trump has called for a better agreement toward fewer weapons, with no preconditions.

Pentagon reports detail China's silo construction, with over 100 loaded with DF-31 ICBMs, and its intent to deter non-nuclear actions via nuclear forces despite its no-first-use policy. The buildup raises concerns over strategic stability as delegations prepare for further Geneva talks.