The United States on Monday (February 23, 2026) accused China of dramatically swelling its nuclear arsenal, and doubled down on claims that Beijing had conducted secret nuclear tests, demanding again it be part of any future arms control treaty.

Washington said the lapsing earlier this month of New START — the last treaty between top nuclear powers, the United States and — Russia presented the possibility of striking a "better agreement" including Beijing.

Christopher Yeaw, the U.S. Assistant Secretary of State for arms control and non-proliferation, told the Conference on Disarmament in Geneva that New START had been seriously flawed and "did not account for the unprecedented, deliberate, rapid and opaque nuclear weapons build-up by China".

"Despite its claims to the contrary, China has deliberately and without constraint, massively expanded its nuclear arsenal without transparency or any indication of China's intent or end point," he charged.

Chinese Ambassador Shen Jian told the conference that his country "firmly opposes the constant distortion and smearing of its nuclear policy by certain countries", insisting that Beijing would not "engage in any nuclear arms race, with any country".