He said: “The scenes coming out of Mariupol and elsewhere are horrific, and the coming weeks will continue to be very difficult.
“But in many ways, Putin has already lost. Far from being the far-sighted manipulator of events that he would have us believe, Putin has damaged himself through a series of catastrophic misjudgements.
“Like all authoritarians, he allowed himself to be misled as to his own strength, including the effectiveness of the Russian armed forces.
“His actions to date have done more to galvanise than divide and have shown Ukraine to have the one thing Russia conspicuously lacks — real friends.
“What is very clear is that Putin is a weaker and more diminished figure today than he was a month ago, and conversely NATO is stronger and more united today than at any time I can remember.”
Sir Tony who is the former head of the Navy went on to argue that there were “early indications” that Russian forces were retreating.
He said: “I think we are seeing that Russia’s ambitions to take Kyiv and Russia’s ambitions to take the whole of Ukraine and do that in a very swift and impressive fashion, those ambitions have fallen apart.
“And it looks now that less emphasis is being placed on Kyiv and more emphasis is being placed on the east and the south.
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It comes after comments made by Sir Jeremy Fleming, the director of GCHQ in a speech in Australia that Putin was facing growing insurrection over the failed war.
Sir Jeremy added that the Russian President had “overestimated” the ability of his military forces.