Mr Burns was asked if he thought Mr Putin was unstable and unhealthy.

“As far as we can tell he’s probably too healthy,” Mr Burns said, before quipping that this was an “informal intelligence judgement”.

The CIA director predicted that the Kremlin would grind on with a war of attrition in the belief that the West’s will to support Ukraine would falter.

But he said Mr Putin had miscalculated with his initial invasion plans, failing to seize Kyiv in a lightning strike, and would be proved wrong again.

“He insists that Ukraine is not a real country, but real countries fight back.”