The United States and Nato will be too scared of a “nuclear apocalypse” to intervene in the war in Ukraine - even if the Kremlin fires the deadly weapons in Europe, Russia's former president Dmitry Medvedev has said.
In another ratcheting up of the rhetoric, Mr Medvedev, who is now deputy chairman of Russia's Security Council, said Russia had the right to defend itself with nuclear weapons if it is pushed beyond its limits and insisted this is "certainly not a bluff".
"I have to remind you again - for those deaf ears who hear only themselves. Russia has the right to use nuclear weapons if necessary," Mr Medvedev said, adding that it would do so "in predetermined cases" and in strict compliance with state policy.
"Let's imagine that Russia is forced to use the most powerful weapon against the Ukrainian regime that has committed a large-scale act of aggression, which is dangerous for the very existence of our state," Medvedev said.
"I believe that Nato would not directly interfere in the conflict even in this scenario. The demagogues across the ocean and in Europe are not going to die in a nuclear apocalypse."
The 57-year-old served as the president of Russia between 2008 and 2012 and prime minister between 2012 and 2020.
He once presented himself as a reformer who was ready to work with the United States to liberalise Russia.
But in recent months he has recast himself as the most publicly hawkish member of Vladimir Putin's circle and repeatedly raised the threat of nuclear chaos.
US yet to respond to latest threat
The US has not yet responded directly to the latest sabre rattling, but over the weekend, Jake Sullivan, National Security Adviser, said Washington would respond decisively to any Russian use of nuclear weapons against Ukraine and has spelled out to Moscow the "catastrophic consequences" it would face.
Any use of nuclear weapons would be the first since the United States unleashed the first atomic bomb attacks on the Japanese cities of Hiroshima and Nagasaki in 1945.
Today, around 90 per cent of the world's nuclear warheads are held by Russia and the United States.
Russia has 5,977 nuclear warheads while the United States has 5,428 warheads. Elsewhere, China has 350, France has 290 and the United Kingdom has 225, according to the Federation of American Scientists.