Vladimir Putin is backed into a corner of his own doing and prepared to use nuclear weapons if his war fails, a military historian claims.
Sir Antony Beevor says the Russian President believes NATO's 'advance' on his own country's borders is the equivalent to the Nazis moving through Europe 80 years ago.
And the push for Finland and Sweden to join the alliance in recent days amid the despot's catastrophic invasion of Ukraine will have done little to ease his misplaced suspicions.
Sir Antony, who has published several books on the Second World War, said Putin genuinely thinks the Red Army fought off Adolf Hitler's Wehrmacht "single-handed" while the western allies wanted to "stab the Soviet Union in the back".
Moscow's current invasion, which it calls a "special operation" to disarm Ukraine and protect it from fascists, has jolted European
security.
Kyiv and its Western allies say the fascism assertion is a baseless pretext for an unprovoked war of aggression.
Writing in the Daily Mail, Sir Antony said: "Ultimately, he has trapped himself in a past that he fails to understand.
"He refuses to acknowledge that it is his own aggressive actions which have achieved that.
"So, combined with his bitter resentment that the West never showed proper 'respect' – that gangster euphemism for 'fear' – Putin wants to terrify us."
Sir Antony, whose latest book Russia : Revolution And Civil War 1917-1921 is released later this month, went on to say Putin's "own disastrous mistakes have backed him into a corner".
He believes the former KGB intelligence officer is prepared to use nuclear weapons if "his own regime" is defeated in Ukraine.
He added: "This has created far greater dangers for the world than at any moment since 1945."
The southeastern region of Donbas has become the main theatre of war over the past month.
Ukraine's counteroffensive there is underway near the Russian-held town of Izium, but its military has reported that Moscow forces are advancing elsewhere.
Having resisted fiercely since Russia launched its invasion on February 24, Ukraine's military has notched a string of successes, first forcing Russia's commanders to abandon an advance on the capital Kyiv, and then making rapid gains in the northeast in recent week to drive the enemy away from the second biggest city of Kharkiv.
Since mid-April, Russian forces have focussed much of their firepower on the east for what has become known as the "Battle of the Donbas".
British military intelligence delivered a damning assessment on Sunday of Russia's campaign in the region.
It reckoned that Russia had lost about a third of the ground combat force deployed in February, and its offensive in the Donbas had fallen "significantly behind schedule" and was unlikely to make rapid advances during the coming 30 days.
Keeping up pressure on Izium and Russian supply lines will make it harder for Moscow to encircle battle-hardened Ukrainian
troops on the eastern front in the Donbas.
One of the aims of Russia's action in Ukraine was to prevent the former Soviet republic ever joining NATO.
But in a telephone call, Finnish President Sauli Niinisto told Russian President Vladimir Putin that his country, which shares a 1,300-km (800-mile) border with Russia, wanted to join the North Atlantic Treaty Organization to bolster its own security.
Putin told Niinisto it would be a mistake for Helsinki to abandon its neutrality, the Kremlin said, adding that the move could harm bilateral relations.
