GENEVA, Feb 24, 2026 (BSS/AFP) - Moscow voiced alarm Tuesday at Washington's assertion it will resume nuclear testing to match alleged secret explosions by China and Russia, warning such a move would spark a dangerous "domino effect".

Speaking before the Conference on Disarmament in Geneva, Russian ambassador Gennady Gatilov decried US President Donald Trump's announcement last year that his country was prepared to stage its first nuclear test since 1992.

"We warn that the US withdrawal from its national moratorium would trigger a domino effect," he said, speaking through a translator, stressing that "the responsibility for the consequences would rest entirely with Washington".

Christopher Yeaw, the US assistant secretary of state for arms control and nonproliferation, indicated last week that Trump was serious when he said in October that the United States would resume nuclear testing.

"As the president has said, the United States will return to testing on a -- quote -- 'equal basis,'" Yeaw said at the Hudson Institute think tank.

He stressed that "equal basis doesn't mean we're going back to Ivy Mike-style atmospheric testing in the multi-megaton range", referring to a massive 1952 thermonuclear detonation in the South Pacific.

"Equal basis, however, presumes a response to a prior standard. Look no further than China or Russia for that standard," he said.

He did not announce a timing for a new test, saying Trump would make a decision, but that any test would be at a "level playing field."

Before the Conference on Disarmament on Monday, Yeaw doubled down on US accusations of Chinese secret nuclear tests.

He provided more details on a low-yield test Washington says Beijing conducted in 2020 and accused China of preparing more explosions with larger yields.

Yeaw told the conference that data gathered in nearby Kazakhstan showed China conducted a 2.75-magnitude explosion underground on June 22, 2020 at 0918 GMT.

"The estimated yield of the event was a 10-tonne nuclear explosion, or five tonnes conventional equivalent, which assumes the explosion was fully coupled in hard rock below the water table," he said.

And "there have been others", a senior US State Department official told reporters in Geneva Monday, asking not to be identified.

"China has planned to conduct tests with designated yields in the hundreds of tonnes," he said.

The United States has also accused Russia of secretly conducting low-yield tests.

"If the world's worried about what kind of testing the United States will conduct, they should be more worried about the basis that's already been set... by Russia and China," the official said.

Gatilov warned Tuesday that the US position added to the challenges facing the Comprehensive Nuclear-Test-Ban Treaty -- a UN treaty that would ban all nuclear explosions but that has so far been unable to take effect.

To date, France and Britain are the only nuclear weapons states to have ratified it.

"The situation around the Comprehensive Nuclear Test Ban Treaty remains challenging," Gatilov said, warning that "actions by the US administration... raise additional doubts about the prospects of the CTBT's entry into force".