Russian parliament completes passage of law shifting stance on nuclear test ban treaty

Russia's parliament completed the passage of a law on Wednesday that withdraws Moscow's ratification of the global treaty banning nuclear weapons tests.

The upper house, the Federation Council approved the law by 156 votes to zero after the lower house, the Duma, had also passed it unanimously. It now goes to President Vladimir Putin for signing.

Putin urged lawmakers earlier this month to make the change in order to "mirror" the position of the United States, which signed but never ratified the Comprehensive Nuclear Test Ban Treaty (CTBT).

Russia says it will not resume nuclear testing unless Washington does, but arms control experts are concerned it may be inching towards a test that the West would perceive as a threatening escalation in the context of the Ukraine war.

Ukraine has accused Russia of stepping up "nuclear blackmail".

Though it has never formally come into force, the CTBT has made nuclear testing a taboo - no country except North Korea has conducted a test involving a nuclear explosion this century.

Arms control experts say a test by either Russia or the United States could trigger a new arms race at a moment of acute international tension, with wars raging in Ukraine and the Middle East. They say if one country tested, the other would likely do the same and others such as China, India and Pakistan could follow.

CNN published satellite images last month showing Russia, the United States and China have all built new facilities at their nuclear test sites in recent years.

The U.S. Energy Department said last week it conducted a chemical explosion at its nuclear test site in Nevada "to improve the United States' ability to detect low-yield nuclear explosions around the world".

Speaking to Russian lawmakers before Wednesday's vote, Deputy Foreign Minister Sergei Ryabkov said the Nevada blast was "undoubtedly a political signal".

"As our president said, we must be on alert, and if the United States moves towards the start of nuclear tests, we will have to respond here in the same way," he said.