This is what a Russian oil tycoon has to say about Putin

An oil tycoon who was formerly Russia's richest man says he thinks Russian President Vladimir Putin "became a criminal" after his invasion of Ukraine.

"This is a man who took the decision that he can kill people and bomb towers for some interest of his own," Mikhail Khodorkovsky told CNN's Nina dos Santos in a Russian-language interview published Friday. "He is my personal enemy, and I think he is the enemy of any normal human being."

Khodorkovsky spent a decade in prison for fraud and tax evasion, charges he said were trumped up due to his support of Putin's opponents in Russia. His grandfather was born in Zhytomyr, Ukraine, and his grandmother was from Kharkiv, which was recently the site of a Russian attack where dozens of casualties were reported.

When it comes to Putin's mindset, Khodorkovsky said there are "features of paranoia" including a fear of even his own inner circle, as well as the belief that he would receive at least some support for his actions in Ukraine.

"I think Putin thought he would be met with flowers in Ukraine, and that he would convince people that he was there to liberate them from these so-called Nazis he keeps going on about," Khodorkovsky said. "Putin is firmly convinced that people themselves can't fight for freedom themselves. It must be some Americans forcing them to do it, and so today he's shocked."

Ukrainians have been fighting back and defending their cities. They’ve built anti-tank obstacles out of scrap metal and removed traffic and directional signs in order to confuse the invading troops. Countries like Canada have also sent Ukraine lethal weapons to defend itself against Russia.

Khodorkovsky said the sanctions in place against Russian assets are a good start, but questioned why they only applied to some Russian banks and oligarchs.

"Any payments in favour of Russia, or in the interest of Russia's regime, must be stopped," he said. "For that, all Russian bank accounts, all accounts that belong to the oligarchs, all of whom act as Putin's wallets – it must be really painful for all until the war stops."

Khodorkovsky said he urges action at any cost, adding that he doesn't put it past Putin to consider using nuclear weapons.

"I think he can cross any lines," he said, speaking in English.

On. Feb. 27, Putin told his top defence and military officials to put nuclear forces in a "special regime of combat duty," but it was not immediately clear how that might have changed the status of Russian nuclear forces, if at all. Canada's Foreign Affairs Minister Mélanie Joly called the nuclear alert order "madness," and Defence Minister Anita Anand said Putin's language was "highly, highly irresponsible."

With strict sanctions hitting Russia from around the globe and little international support for the invasion of Ukraine, Khodorkovsky said he does not think Putin will remain in office for long.

"Maybe a year, maybe three," he said. "But what he's done in Ukraine has significantly reduced his chances of remaining in power much longer. Today we are no longer thinking in terms of him being around another decade, as we thought a week ago."

With files from CNN, The Associated Press and Sarah Turnbull.