Any actions or language deemed escalatory, such that Putin believes his rule could be at risk, should therefore be handled extremely carefully.

In February, he said in a televised statement: “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 later ordered the Russian Army Deterrence Force, Moscow’s nuclear units, to be placed on “combat alert“.

Putin has not always so obviously equated his own survival with that of the state, but has “been on that path for the past few years”, Ms Braw said.

“He has accelerated down that authoritarian path, particularly in recent months,” she added.

Comparisons with Adolf Hitler are generally unhelpful, she said, but added the Russian leader’s mindset may have destabilised in recent months to be close to that of Hitler’s in 1945.

“At the end of the war, Hitler decided that he didn’t care what happened to Germany, the country was going to go down with him,” said Ms Braw.

“I wonder if Putin has reached that stage. He clearly doesn’t care what’s happening to ordinary Russians.

“Even in the days of the Soviet Union, the Politburo was a collective decision-making organ. The chairman was the head of state but there were different factions and rivalries and other powerful people within the Politburo.

“In Russia today, there is just him.”