Russian President Vladimir Putin said on Monday that there could be "no winners" in a nuclear war and it should "never be unleashed."
He made the statement as a review of the keystone nuclear treaty opened at the United Nations.
In an address to the Tenth Nuclear Proliferation Treaty (NPT) Review Conference, Putin insisted that Russia remained faithful to the treaty's "letter and spirit."
"There can be no winners in a nuclear war and it must never be unleashed," he said.
They contrasted with earlier statements by Putin and other Russian politicians that have been interpreted in the West as implicit nuclear threats.
In a speech on Feb. 24, as he launched the Russian invasion of Ukraine, Putin pointedly referred to Russia's nuclear arsenal and warned outside powers that any attempt to interfere would "lead you to such consequences that you have never encountered in your history".
Days later, he ordered Russia's nuclear forces to be put on high alert.
The war has raised geopolitical tensions to levels not seen since the 1962 Cuban Missile Crisis, with politicians in both Russia and the United States speaking publicly of the risk of World War Three.
On Monday, the United States, Britain and France rebuked Russia for "irresponsible and dangerous" talk about possibly deploying nuclear weapons.
Since the start of Moscow's military intervention in Ukraine, Putin has made thinly veiled threats hinting at a willingness to deploy Russia's tactical nuclear weapons, which Russian military doctrine holds can be used to force an adversary to retreat.
Russian state propaganda has also argued for using nuclear weapons in the conflict.
In May, Russian editor and Nobel Peace Prize laureate Dmitry Muratov warned that the Kremlin's "propaganda warriors" were striving to make nuclear weapons use more palatable to the Russian public.
