The former president blamed Joe Biden’s “weakness and stupidity” minutes after the first report of explosions in Ukraine. Mr Trump told Fox News: “I knew [Putin] wasn’t going to be satisfied with a piece [of Ukraine] and now he sees the weakness, incompetence and the stupidity of this administration.
“As an American I’m angry about it and saddened by it. The whole thing should never have happened and it would never have happened during my administration.”
Mr Trump added he believed Mr Putin felt emboldened after the botched US withdrawal from Afghanistan.
He said: “I think he wanted to do something and negotiate and it just got worse. Then he saw the weakness, it really started I think with the weakness in Afghanistan. I think that’s when he started thinking he could do this.”
After Mr Biden issued a statement saying he would be “monitoring” events in Ukraine, Mr Trump said: “I don’t think [Mr Biden] is monitoring. He’s probably sleeping.”
The former president accused Mr Biden and Barack Obama of driving Russia and China together.
He said: “As a young man growing up I heard the worst thing you could do is drive those two countries together. I kept them apart. Now, it’s a great love-fest and it’s a bad thing.”
Mr Biden said on Thursday: “President Putin has chosen a premeditated war that will bring a catastrophic loss of life and human suffering.
“I will be meeting with the leaders of the G7 and the United States and our allies and partners will be imposing severe sanctions on Russia.”
READ MORE ABOUT PUTIN LAUNCHING RUSSIA’S ATTACK ON UKRAINE
Explosions have been heard near Ukraine’s capital, Kiev, and in other parts of the country. Ukrainian President Volodymyr Zelenskiy said Russia carried out missile strikes on infrastructure.
He appealed to world leaders to impose all possible sanctions on Russia, including on Mr Putin, saying the Kremlin leader wanted to destroy the Ukrainian state.
Prime Minister Boris Johnson is leading a crisis meeting of senior ministers and officials to consider how to respond to Russia’s attack.
The PM said Mr Putin has “chosen a path of bloodshed and destruction”. Mr Johnson is expected to announce further sanctions.
The meeting of the Cobra emergency committee follows a call between Mr Johnson and Mr Zelensky during the night as Russia launched its assault.
Mr Johnson – whose initial package of sanctions was criticised by senior Tories and opposition figures – has promised to respond “decisively” to the Russian onslaught.
He said: “I am appalled by the horrific events in Ukraine and I have spoken to President Zelensky to discuss next steps.
“President Putin has chosen a path of bloodshed and destruction by launching this unprovoked attack on Ukraine. The UK and our allies will respond decisively.”
European Commission President Ursula von der Leyen said Mr Putin is responsible for bringing war back to Europe.
She added: “We will target strategic sectors of the Russian economy by blocking their access to key technologies and markets. We will weaken Russia’s economic base and its capacity to modernise.
“In addition, we will freeze Russian assets in the EU and stop the access of Russian banks to the European financial market.”
Central European countries have condemned Russia’s attack and begun preparations to receive potentially hundreds of thousands of people fleeing Ukraine. China called for all parties involved in the situation in Ukraine to exercise restraint.