MOSCOW, Nov 2 (Reuters) - President Vladimir Putin on Thursday (Nov 2) signed a law withdrawing Russia's ratification of the global treaty banning nuclear weapons tests, a step condemned by the organisation which promotes adherence to the landmark arms control pact.

The move, though expected, is evidence of the deep chill between the United States and Russia, whose ties are at their lowest level since the 1962 Cuban missile crisis over the war in Ukraine and what Moscow casts as Washington's attempts to stymie the emergence of a new multipolar world order.

Moscow says its deratification of the Comprehensive Nuclear Test Ban Treaty (CTBT) is merely designed to bring Russia into line with the United States, which signed but never ratified the treaty. Russia will not resume nuclear testing unless Washington does, say Russian diplomats.

Nor, they say, will the move change the nuclear posture of Russia, which has the world's largest nuclear arsenal, or the way it shares information about its nuclear activities as Moscow will remain a treaty signatory.

But some Western arms control experts are concerned that Russia may be inching towards a nuclear test to intimidate and evoke fear amid the Ukraine war.

Putin said on Oct 5 that he was not ready to say whether or not Russia should resume nuclear testing after calls from some Russian security experts and lawmakers to test a nuclear bomb as a warning to the West.

Such a move, if it did happen, could usher in a new era of big power nuclear testing.

Robert Floyd, head of the Comprehensive Nuclear-Test-Ban-Treaty Organization, whose job is to promote recognition of the treaty and build up its verification regime to ensure no nuclear tests go undetected, condemned Russia's step.

Photo from AFP