Fears in Washington that Covid isolation has unbalanced Vladimir Putin

He added: “But most telling is this is a man who has long prided himself on emotional control. His recent flashes of anger is very uncharacteristic and show an erosion in impulse control.”

America was not dealing with the Vladimir Putin of 2008, he added.

While stopping short of questioning Putin’s sanity, White House press secretary Jen Psaki did question his state of mind.

“He’s obviously been quite isolated during Covid. But I will tell you, certainly the rhetoric, the actions, the justification that he’s making for his actions are certainly deeply concerning to us,” she told ABC’s This Week.

In September Putin went into isolation after members of his inner circle tested positive for the virus. Then in October last year, he was seen coughing during a televised government meeting.

But he dismissed suggestions that he had contracted the virus.

“Don’t worry, everything is fine. They test me practically on a daily basis not just for Covid-19 but all kinds of other infections, so it’s all good,” he said.

HR McMaster, who served as National Security Adviser under Donald Trump, told CBS news that Putin was “not a rational actor”.

He added that the Russian president was fearful about retaining control of the country.