A senior U.S. State Department official has delivered one of Washington’s starkest warnings yet about China’s rapidly expanding nuclear ambitions, accusing Beijing of secretly testing nuclear weapons while publicly claiming restraint.
Speaking before the United Nations–backed Conference on Disarmament in Geneva, U.S. Assistant Secretary of State for Arms Control and Non-Proliferation Christopher Yeaw said China is quietly accelerating its nuclear buildup — and may soon rival the world’s two largest atomic powers.
“Despite its claims to the contrary, China has deliberately and without constraint massively expanded its nuclear arsenal,” Yeaw told delegates, adding that Beijing has provided “no transparency” about its intentions or ultimate goals.
Secret Test Allegedly Detected
At the center of the dispute is a suspected low-yield nuclear detonation carried out at China’s remote Lop Nur testing site on June 22, 2020.
According to newly declassified U.S. intelligence presented at the conference, the explosion had an estimated yield equivalent to roughly a 10-ton nuclear device — small by modern standards but significant enough to register seismic activity across the border in Kazakhstan.
American officials say the test was not accidental.
Instead, they allege the People’s Liberation Army used advanced concealment techniques designed to evade international monitoring systems tasked with detecting nuclear explosions worldwide.
Under Secretary of State for Arms Control Thomas DiNanno accused China of deliberately masking its activity.
“The PLA sought to conceal testing by obfuscating nuclear explosions,” DiNanno said. “They used decoupling methods specifically intended to weaken seismic detection.”
U.S. officials claim those tactics allowed the blast to slip past international verification mechanisms tied to the Comprehensive Test Ban Treaty (CTBT).
Treaty Limits — Without China
The accusations highlight a growing frustration inside Washington over the structure of global arms control agreements.
While both the United States and Russia limited portions of their nuclear arsenals under the now-expired New START treaty, China’s weapons were never included.
“Zero Chinese nuclear weapons were covered,” DiNanno noted, arguing that the agreement’s biggest flaw was ignoring Beijing’s rapid military expansion.
American analysts now believe China could achieve nuclear parity with the United States and Russia within the next four to five years — a dramatic shift in the global balance of power.
For decades, Beijing maintained that it sought only a minimal deterrent force. U.S. officials now say the evidence points to something far larger.
“China’s entire nuclear arsenal has no limits, no transparency, no declarations, and no controls,” DiNanno warned.
Beijing Rejects the Claims
China swiftly denied the accusations.
Ambassador Jian Shen dismissed the U.S. presentation as politically motivated, calling the allegations “completely unfounded” and accusing Washington of using them as justification to resume American nuclear testing.
“The U.S.’s practice of smearing other countries to evade international obligations damages its own standing,” Jian said.
The dispute underscores widening distrust between the world’s major powers as arms control frameworks built during the Cold War era continue to unravel.
Testing Could Resume
The controversy comes amid renewed debate in Washington over whether the United States should restart nuclear weapons testing for the first time since 1992.
President Donald Trump has previously suggested testing could resume if rival powers continue developing new weapons systems.
“With others doing testing, I think it’s appropriate that we do also,” Trump said following discussions with Chinese leadership last year.
Administration officials indicated in Geneva that renewed U.S. testing could be avoided — but only if a new trilateral arms agreement including China and Russia emerges.
A New Nuclear Era?
Behind the diplomatic language lies a deeper concern: the world may be entering a new nuclear arms race without the guardrails that once constrained superpower competition.
American officials argue that secrecy surrounding China’s program makes strategic stability increasingly difficult, raising the risk of miscalculation among nuclear powers.
DiNanno framed the stakes bluntly before the conference:
“Together, we can prevent an unmitigated nuclear arms race… but only if transparency and accountability return.”
Whether that cooperation materializes remains uncertain. Talks between U.S., Russian, and Chinese representatives are ongoing in Geneva, but positions remain far apart.
For now, Washington’s message is clear: the era of assuming China’s nuclear arsenal would remain small may be over — and the consequences could reshape global security for decades.