Vladimir Putin will only resort to using nuclear weapons if Russia faces an "existential threat" - possibly with NATO troops bearing down on Moscow - a former foreign minister has claimed.
Andrei Kozyrev, who served under Putin's predecessor Boris Yeltsin in the 1990s, played down fears that the irrational Russian president may unleash the country's nuclear arsenal any day now.
International experts are split on how likely this is, with his invasion of Ukraine not going to plan.
Mr Kozyrev, Minister of Foreign Affairs of the Russian Federation between 1990 and 1996, told Fox News : "They could be used, but in very, very specific situations.
"If Russia or one of those countries really threatened in their hearts – existentially, that is … if NATO troops come to Moscow, then probably they will resort to nuclear weapons."
But he said this scenario is a long way away at the moment.
He said: "But there is no existential threat to Russia under the present circumstances."
At the weekend Ukrainian President Volodymyr Zelensky warned that Putin could turn to chemical or nuclear weapons.
He told CNN : "Not only me - all of the world, all of the countries have to be worried because it can be not real information, but it can be truth."
The Ukrainian president continued: "Chemical weapons, they should do it, they could do it, for them the life of the people, nothing. That's why.
"We should think not be afraid, not be afraid but be ready. But that is not a question for Ukraine, not only for Ukraine but for all the world, I think."
These fears were echoed by Prof Nina Khrushcheva, great-granddaughter of former Soviet leader Nikita Khrushchev.
Khrushcheva, a professor of International Affairs at The New School in New York City, said she is fearful that Putin may turn to nuclear weapons.
She told Newsweek : "Since there are questions about how far Russia can go to create victory, and nuclear weapons have been part of the conversation on both sides, Russian and the West, the tactical atomic option is potentially imaginable."
She added that her remarks are "not a prediction."
Putin today said Western countries had scored an own goal by imposing sanctions against Russia over Ukraine which he said had led to a "deterioration of the economy in the West".
Speaking on the state of Russia's domestic economy, Putin said that inflation was stabilising and that retail demand in the country had normalised.
Western countries have imposed unprecedented sanctions on Russia's corporate and financial system since it sent troops into Ukraine on February 24.
