Vladimir Putin
Vladimir PutinReuters

Former Russian President Dmitry Medvedev said on Tuesday that Russia has the right to defend itself if pushed and the threat of nuclear weapons “is certainly not a bluff”, The Independent reported.

Medvedev, who is now deputy chairman of Russia’s Security Council, added that the US-led military alliance NATO would stay out of the conflict for fear of a “nuclear apocalypse”.

"Let’s imagine that Russia is forced to use the most fearsome weapon against the Ukrainian regime which had committed a large-scale act of aggression that is dangerous for the very existence of our state," he posted on Telegram, as quoted in The Independent.

"I believe that NATO would not directly interfere in the conflict even in this scenario," added Medvedev. "The demagogues across the ocean and in Europe are not going to die in a nuclear apocalypse."

According to Russia’s nuclear doctrine, the president can order the usage of nuclear weapons if the state faces an existential threat, including from conventional weapons.

"I have to remind you again - for those deaf ears who hear only themselves. Russia has the right to use nuclear weapons if necessary," Medvedev said, adding that it would use it “in predetermined cases” while complying with the state policy.

Russian President Vladimir Putin issued a thinly veiled nuclear threat in a speech last week in which Putin also announced his country's first wartime military mobilization since World War Two.

US President Joe Biden, in his speech at the United Nations General Assembly, accused Putin of making "overt nuclear threats against Europe" in reckless disregard for nuclear nonproliferation responsibilities.

On Sunday, US National Security Adviser Jake Sullivan warned that the United States would respond decisively to any Russian use of nuclear weapons against Ukraine and has spelled out to Moscow the "catastrophic consequences" it would face.

"If Russia crosses this line, there will be catastrophic consequences for Russia. The United States will respond decisively," Sullivan told NBC's "Meet the Press" program.

He did not describe the nature of the planned US response in his comments on Sunday but said the United States has privately to Moscow "spelled out in greater detail exactly what that would mean."