"Unfortunately, it represents a significant step in the wrong direction, taking us further from, not closer to, entry into force" of the treaty, Blinken said in a statement.

"This continues Moscow's disturbing and misguided effort to heighten nuclear risks and raise tensions as it pursues its illegal war against Ukraine," he said.

"Russian officials say Russia's planned move to withdraw its ratification does not mean that it will resume testing, and we urge Moscow to hold to those statements."

The United States as well as China, unlike Russia, have never ratified the treaty, a key obstacle for it coming into force.

President George H.W. Bush in 1992 signed into law a unilateral ban on US nuclear testing that has since been extended. But the Senate rejected ratifying the test ban treaty in 1999.

President Joe Biden and his Democratic predecessors have supported ratification but treaties under the US Constitution require two-thirds support, a prohibitive threshold with many Republicans wary of any international limits on US power.