The Russian President has previously discussed using nuclear weapons against nations that he believes pose a threat to Russia. “No matter who tries to stand in our way or all the more so create threats for our country and our people, they must know that Russia will respond immediately, and the consequences will be such as you have never seen in your entire history,” he said in a televised statement in February.

In a later televised meeting with the Kremlin’s defence chiefs, he said, “officials in leading NATO countries have allowed themselves to make aggressive comments about our country, so I hereby order the Minister of Defense and the Chief of the General Staff to place the Russian Army Deterrence Force on combat alert.”

During an interview with CNN on Tuesday, Putin’s chief spokesman, Dmitry Peskov, repeatedly refused to rule out Russia using nuclear weapons to counter what Moscow saw as a “existential threat.”

When asked under what circumstances Putin would use Russia’s nuclear capability, Peskov responded, “if it is an existential threat to our country, then it can be.”

When asked about Ukraine and what the Russian President has accomplished as a result of it, Mr Peskov told CNN, “First and foremost, not yet.” He hasn’t accomplished anything yet.”

The spokesman also claimed that the “special military operation,” the Kremlin’s dubious justification for Russia’s invasion of Ukraine, was “going on strictly in accordance with the plans and purposes that were established beforehand.”

Meanwhile, the Russian advance, according to Western intelligence agencies, is stalling as Putin’s troops take defensive positions in their attempt to encircle major Ukrainian cities.

Mariupol’s 100,000 residents are still trapped in the strategic southern port city on which Russia has focused its efforts.

According to President Zelensky’s nightly Facebook address, approximately 7,000 Mariupol residents were rescued on Tuesday.

Mr Peskov echoed Putin’s demands during the interview, saying that the “main goals of the operation” are to “get rid of Ukraine’s military potential,” to ensure the ex-Soviet state is a “neutral country,” to get rid of “nationalist battalions,” for Ukraine to accept that Crimea, which Putin annexed in 2014, is part of Russia, and to accept that the breakaway statelets of Luhansk and Donetsk “are already independent.”

The US Pentagon slammed the statement as reckless, stating that “it is not the way a responsible nuclear power should act.”

When asked about Peskov’s remarks and Russia’s nuclear posture in general, Pentagon spokesman John Kirby called Moscow’s rhetoric on the potential use of nuclear weapons “dangerous.”