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The United States has now accused China of rapidly expanding its nuclear arsenal in secret while resisting transparency and participation in renewed arms control negotiations.

Getting into it: While speaking at the Conference on Disarmament in Geneva, Assistant Secretary of State for Arms Control and Non-Proliferation Christopher Yeaw said China has “deliberately and without constraint, massively expanded its nuclear arsenal without transparency or any indication of China’s intent or end point.” He also claimed that “Beijing is on track to have the fissile material necessary for more than 1,000 nuclear warheads by 2030,” warning that such growth fundamentally alters the strategic balance.

Yeaw tied those claims to the recent expiration of the New START treaty with Russia, arguing that its “greatest flaw” was that it “did not account for” China’s buildup. The push aligns with President Donald Trump’s renewed effort to bring China into a nuclear deal with Russia, after previous attempts at trilateral talks failed during his first term.

The accusations come weeks after US officials publicly claimed that China conducted a covert low-yield nuclear test in 2020. Yeaw said data gathered from monitoring stations in Kazakhstan detected a 2.75 magnitude underground explosion on June 22, 2020, which he described as a “probable explosion” with an estimated yield of “a 10-tonne nuclear explosion, or five tonnes conventional equivalent.” He further alleged that “there have been others” and suggested China may be preparing additional tests with significantly larger yields.

Yeaw also criticized China’s resistance to greater international monitoring, saying China has made it “difficult” for the global community to verify its activities. He pointed to what he described as a lack of transparency about China’s nuclear “endpoint” and accused Russia of helping “boost Beijing’s capacity to increase its arsenal size.”

This all comes as China has rejected the US claims. At the same Geneva conference, Ambassador Shen Jian said Beijing “firmly opposes the constant distortion and smearing of its nuclear policy by certain countries.” He called the allegations of a nuclear test “completely unfounded” and accused Washington of using them “as a pretext” to resume its own testing.

Shen also insisted that China would not “engage in any nuclear arms race, with any country,” and argued that “China’s nuclear arsenal is not on the same scale as the country with the largest nuclear arsenal,” maintaining that it is “not fair, reasonable or realistic” to expect China to participate in trilateral nuclear talks.