Russia’s parliament took the first step this week toward revoking ratification of the Comprehensive Test Ban Treaty and a top lawmaker warned the United States that Moscow may abandon the treaty altogether.

Russia says the move is an effort is to restore nuclear parity with the United States, which has signed but never ratified the 1996 treaty, and that it will not resume testing unless Washington does.

But arms control experts are concerned that Russia may be inching towards a test that could usher in a new nuclear arms race among major powers — and which the West would perceive as a Russian nuclear escalation amid the Ukraine war.

The move comes amid heightened activity at Novaya Zemlya, an old Soviet-era atomic bomb testing range in the high Arctic — though Bellona experts have not observed any moves that would indicated an eminent nuclear bomb test.

Parliament’s lower house, the Duma — largely a rubber stamp for the Kremlin — voted Thursday 415 to zero, to approve the withdrawal of the ratification in the third of three readings of the bill. The legislation will now go to the Federation Council — the Duma’s upper house and another pro-Kremlin body — before it goes to President Vladimir Putin for his signature.

“Washington must finally understand that hegemony on their part does not lead to anything good,” Duma Speaker Vyacheslav Volodin, a member of President Vladimir Putin’s Security Council wrote Tuesday on his Telegram channel. “The Russian Federation will do everything to protect its citizens and ensure that global strategic parity is maintained.”

The treaty concluded in 1996 bans nuclear-test explosions of any size. It allows a range of activities to ensure the safety and reliability of nuclear weapons, including experiments involving fissile material, so long as they don’t produce a nuclear explosive yield.

Though the treaty isn’t legally in force because it hasn’t been ratified by enough nations, major powers including Russia, the US and China say they are abiding by its terms.

Russia’s decision to step back from the pact comes at a time when arms talks between Washington and Moscow have all but frozen. Moscow has halted its participation in the New START strategic arms treaty, and relations between Washington and Moscow are severely strained.

Putin has accused the US of fomenting the war he launched in Ukraine last year, charging that Washington’s support for so-called color revolutions — Moscow’s term for pro-democracy upheavals occurring in Ukraine in 2014 and elsewhere in subsequent years — threaten Russia. The US has provided millions of dollars in military assistance to Kyiv as it struggles to push Russian troops out of its country.

Bellona analysts who are following US-Russia relations from Vilnius say that though the withdrawal telegraphs an increased willingness to test nuclear weapons, an actual test is still improbable in the near future.

“So far, all signals and statements from the Russian Foreign Ministry and President Vladimir Putin himself indicate that Russia intends to maintain all obligations under the treaty and its own moratorium on testing,” said Dmitry Gorchakov, a nuclear expert with Bellona’s Environmental Transparency Center in Vilnius.  “They say only that if the United States starts testing first, they will respond in kind. It’s a purely political story aimed at the USA.”

But the move puts the world on a slippery slope, Gorchakov added.

“Withdrawal from ratification is another — and far from first step — on the path of nuclear escalation taken by Russia in recent years. We have already seen the suspension of the implementation of the START treaty and the demonstration of the development of new types of nuclear weapons, and before that the withdrawal from the INF Treaty (IRNFT) and the agreement about the disposal of weapons-grade plutonium,” he said.  “And Putin still has a number of similar symbolic and practical steps ahead before he decides on a real nuclear explosion at a test site. But at the end of this dangerous road is a nuclear war. And along the way, not only relations between Russia and the United States are collapsing , but so is the entire architecture of global collective security.”

Following Putin’s remarks on the treaty earlier this month, a US State Department spokesman said that the Russian move “needlessly endangers the global norm against nuclear explosive testing.” He said the U.S. remained committed to observing a moratorium.

In his remarks last month, Putin said that he wasn’t yet prepared to say whether Russia needed to carry out nuclear tests. His spokesman Dmitry Peskov told reporters last week that rescinding ratification of the nuclear test ban didn’t mean that Russia planned to conduct nuclear tests.

Russia’s deputy foreign minister Sergei Ryabkov told reporters in the State Duma last week that Moscow would only resume nuclear tests if Washington were to take that step first.

Gorchakov added that the recent flurry of activity at Novaya Zemlya, north of the Murmansk region, fit a pattern of trying to keep Washington off balance.

“The fuss at the Novaya Zemlya is primarily designed for psychological pressure and aims to demonstrate activity and preparation for tests — and only secondly is it really preparation for them. The won’t happen right now,” Gorchakov said.