Putin, the ultimate decision maker in the world's biggest nuclear power, also said Moscow had successfully tested a nuclear-powered and nuclear-capable cruise missile - the Burevestnik - whose capabilities he has called unmatched.

The Kremlin chief said there was no need to change Russia's nuclear doctrine however, as any attack on Russia would provoke a split-second response with hundreds of nuclear missiles that no enemy could survive.

"Do we need to change this? And why? Everything can be changed but I just don't see the need for it," Putin said of the nuclear doctrine - the Kremlin policy setting out the circumstances when Russia might use its weapons.

The existence of the Russian state was not under threat, he added. "I think no person of sound mind and clear memory would think of using nuclear weapons against Russia," Putin told a meeting of the Valdai Discussion Club in the Black Sea resort of Sochi.

"I hear calls to start testing nuclear weapons, to return to testing," Putin added, referring to suggestions from hardline political scientists and commentators who say such a move could send a powerful message to Moscow's enemies in the West.

NUCLEAR TEST?

He noted that the United States had signed the Comprehensive Nuclear-Test Ban Treaty but not ratified it while Russia had signed and ratified it.

"I am not ready to say whether we really need to conduct tests or not, but it is possible theoretically to behave in the same way as the United States," Putin said.

"But this is a question for the deputies of the State Duma (lower house of parliament). Theoretically, it is possible to withdraw this ratification. That would be enough," he said.

He was answering a question from hardline Russian political scientist Sergei Karaganov who wants a tougher nuclear stance. Karaganov asked if Putin should lower the nuclear threshold to sober up Russia's "insolent" partners.

Inside Russia, some have called for Putin to detonate a nuclear bomb to show the West that Moscow's patience over its support for Ukraine and apparent unwillingness to negotiate is wearing thin.

Most recently, Margarita Simonyan, the editor-in-chief of state-funded broadcaster RT, suggested that Russia should detonate a nuclear bomb over Siberia.

In the five decades between 1945 and the 1996 Comprehensive Nuclear Test-Ban Treaty, more than 2,000 nuclear tests were carried out, 1,032 of them by the United States and 715 of them by the Soviet Union, according to the United Nations.

The Soviet Union last tested in 1990. The United States last in 1992.

A resumption in nuclear tests by Russia, the United States or both would be profoundly destabilising at a time when tensions between the two countries are greater than at any time since the 1962 Cuban Missile Crisis.

In February, Putin suspended Russia's participation in the New START treaty that limits the number of nuclear weapons each side can deploy.

Putin said on Thursday that Russia had almost finished work on its new generation of Sarmat intercontinental ballistic missiles, which are capable of carrying 10 or more nuclear warheads.

And Russia, he said, had also successfully tested the Burevestnik nuclear-powered cruise missile. He did not say when.

UKRAINE

Putin accused the West of losing touch with reality over the Ukraine war. If its leaders had forgotten how to compromise then the world would have to see where such arrogance led, he warned.

Putin said it was the West that had fomented the conflict in Ukraine, which he cast as part of a much larger struggle between Russia and an arrogant West.

"Our interlocutors in the West seem to have completely forgotten that there are such concepts as reasonable self-restraint, compromises, willingness to give in to something in order to achieve an acceptable result for everyone," Putin said.

"They are literally obsessed with only one thing - to push their interests at any cost. If that's their choice, let's see what comes of it."

As he spoke the rouble weakened beyond 100 per U.S. dollar. The rouble was trading at around 80 per U.S. dollar the day before Putin ordered troops into Ukraine on Feb. 24, 2022.

Russia's full-scale invasion of Ukraine, something it calls a "special military opeeration", unleashed a war that has devastated swathes of eastern and southern Ukraine, killed or injured hundreds of thousands of men and triggered the biggest rupture in Russia's ties with the West for six decades.

The West casts the war as Moscow's biggest strategic blunder since the 1979 Soviet invasion of Afghanistan, and Western leaders say they are arming Ukraine to enable it to defend itself and defeat Russian forces.

A Ukrainian counteroffensive this year has so far failed to yield major territorial success. Ukraine, which casts the war as an imperial style land grab by Russia, says it will not rest until every last Russian soldier is ejected from Ukraine.