'After this Putin is finished': Military experts say Russian leader has bitten off more than he can chew with 'massively foolish' invasion of Ukraine and it marks the start of the end of his time in power even if Kyiv falls

 Vladimir Putin could be 'finished' by the invasion of Ukraine after under-estimating military, social and economic resistance at home and abroad, a military expert has suggested.

Professor Michael Clarke said that sending soldiers to take Kyiv was 'massively foolish' and could become a 'peak Putin' moment that leads eventually to his downfall.

Russian forces are widely seen as having struggled in the face of Ukrainian military resistance and civil disobedience since entering the country 11 days ago.

Today president Volodymyr Zelensky vowed that 'God will not forgive' and Ukraine 'will not forget' the slaughter of civilians by Russian forces, saying a 'day of judgement' is coming for them as Moscow was slammed for opening up 'humanitarian corridors' for civilians to flee - with routes leading into Russia itself.

Speaking to BBC Radio 4's Westminster Hour, Prof Clarke said 'every day the Ukrainian government is still up and running and standing is a political victory for them and a political defeat for Russia'.

'The Russians can occupy the country at a superficial level. But given that the Ukrainians now hate them - and you are talking about a big country, a physically big country of 45 million people - it is a sheer impossibility that the Russians can control Ukraine in the way that they thought likely or the way Putin thought likely,' he said.

'It’s a completely impossible scenario Putin has set his military forces, it’s a huge strategic blunder, which incidentally has now become a political crisis in Russia … this is peak Putin. After this Putin is finished. 

Professor Michael Clarke said that sending soldiers to take Kyiv was 'massively foolish' and could become a 'peak Putin' moment that leads eventually to his downfall.

 Speaking to BBC Radio 4's Westminster Hour, Prof Clarke said 'every day the Ukrainian government is still up and running and standing is a political victory for them and a political defeat for Russia'.

Russian forces are widely seen as having struggled in the face of Ukrainian military resistance and civil disobedience since entering the country 11 days ago.

'We don't know how long it will take, it may be some years or it might actually be quite quick. But there is no way out for this, it is a massive massive mistake on his part.'

Zelensky, in a late-night address to his countrymen on the Orthodox Christian holiday of 'Forgiveness Sunday', recalled how a family of four were among eight civilians killed by Russian mortars while trying to flee the city of Irpin - near Kyiv - earlier in the day. 'We will not forgive. We will not forget,' he told listeners.

'We cannot forgive the hundreds upon hundreds of victims. Nor the thousands upon thousands who have suffered,' he added. 'God will not forgive. Not today. Not tomorrow. Never.' 

Ukraine claims to be inflicting heavy losses on the invading Russians, with the ministry of defence claiming to have taken out more than 11,000 troops, some 290 tanks, 1,000 armoured personnel carriers, 46 planes, 68 helicopters and 117 artillery pieces as-of Monday morning. 

None of those figures has been independently verified. Russia has acknowledged taking losses, but gave a figure of 500 deaths last week and has not updated it since.

There were unconfirmed reports early Monday of heavy Russian losses around the captured city of Kherson overnight - with dozens of helicopters taken out alongside artillery columns - but these have also not been verified.

The exact number of civilian casualties is unclear, though is estimated by Ukraine to be in the thousands as residential areas of major cities are indiscriminately bombed using thermobaric and cluster munitions amid evidence of 'hit squads' targeting civilian vehicles. The UN estimates that 1.5million people have fled the fighting. 

Prof Clarke added: 'He (Putin) has taken on a country that does not want to be invaded because for some range of reasons he became obsessed with Ukraine and trying to use it as a lever to reset the whole European security architecture since the end of the cold war. It’s massively, massively foolish on his part.'

Yesterday the UK's top military commander suggested Vladimir Putin's 'decimated' forces could lose the war in Ukraine.

Admiral Sir Tony Radakin said Russia's troops were 'in a mess' and the invasion was 'not going well'.

His comments yesterday represent the most optimistic assessment yet of how the conflict may end – but came on another bleak day, with Russian forces firing on families as they fled the fighting.

When the invasion began less than a fortnight ago it was assumed to be inevitable that Russian tanks would roll into Kyiv within hours. But after a series of strategic blunders and the remarkable resistance of Ukrainian troops on the battlefield, the outcome of the campaign could now be in doubt.

Sir Tony, the former head of the Royal Navy, who was appointed Chief of the Defence Staff late last year, was speaking after eight Russian aircraft were shot down in 24 hours.

The Russians, contrary to their military doctrine, have also been forced to admit that almost 500 of their soldiers have been killed.

And in a highly embarrassing example of ineptitude, a convoy of hundreds of Russian vehicles and an estimated 15,000 troops has ground to a halt.

The column, including tanks, missile batteries and armoured personnel carriers, had been earmarked by Putin to encircle Kyiv and pound the Ukrainians into submission.

But this operation is considered at least a month behind schedule, according to UK military sources. Given the unified approach to sanctions that the UK, US and other world powers have displayed, the Kremlin chief may not be able to sustain a military campaign for that long.

Asked on the BBC yesterday whether Russia taking over Ukraine was 'inevitable', Sir Tony said: 'No. I think we've seen a Russian invasion that is not going well.

'I think we're also seeing remarkable resistance by Ukraine, both its armed forces and its people and we're seeing the unity of the whole globe coming together, applying pressure to Russia.

'Russia is suffering, Russia is an isolated power. It is less powerful than it was ten days ago. Some of the lead elements of Russian forces have been decimated by the Ukrainian response.

'You've also seen basic failures in terms of maintenance and their kit failing. Russia hasn't operated at this scale since the Second World War and it is incredibly complex and difficult.'