Pro-Russian rebels evacuate civilians from the the Donetsk region of Ukraine, ITV News Global Security Editor Rohit Kachroo reports
Speaking from the White House President Joe Biden said: "As of this moment, I am convinced he's [Mr Putin] made the decision."
President Biden has previously said he did not think Mr Putin had made up his mind, making today's announcement a shift in stance by the US.
ITV News Security Editor Rohit Kachroo said this was also the view of US intelligence and they expected the Russians to rush and take Kyiv.Mr Biden also said he had been in regular conversation with NATO and the EU and all were working together to coordinate their response.
The US president believes an invasion would directly hit the capital of Kyiv, ITV News US Correspondent Emma Murphy reports
He said a recent rise in Russian disinformation could be a sign an invasion is imminent.
Mr Biden said the Russians had claimed Ukraine was behind a recent attack on a Ukrainian kindergarten and that the Ukrainians were preparing to invade rebel-held areas.
He said: "Look, there is no evidence [of] these assertions, and it defies basic logic to believe the Ukrainians would choose this moment, with well over 150,000 troops arrayed on its borders, to escalate a year-long conflict."
He added: "All of these are consistent with the playbook the Russians have used before."
Earlier on Friday Ukrainian separatists in eastern Ukraine announced that civilians in the Donetsk region of Ukraine were being evacuated to Russia.
Evacuation sirens sound in the separatists regions of Ukraine as locals flee to Russia
In an emergency broadcast Denish Pushilin, the head of the separatist government in the Donetsk region, said women, children and the elderly will be evacuated first, and that Russia had prepared facilities to accommodate them.
However, the metadata of the video of Pushilin appears to show the video was recorded two days ago.
Videos shared online showed thousands of people fleeing the area.
Mr Putin ordered his emergencies minister to fly to the Rostov region bordering Ukraine to help organise the exodus and ordered the government to offer a payment of 10,000 rubles to each evacuee, equivalent to about half of an average monthly salary in the war-ravaged Donbas.
There was also a car bombing in Donetsk, but there is very little information about the blast although it is believed no one was hurt.
Members of the UK and US intelligence community said these actions are part of a Russian 'false flag operation.'
What is a false flag operation?
A false flag is a form of deception used to justify a conflict and make it appear like the attacker is in fact defending itself.
Usually, the aggressor stages a political or military action carried out with the intention of blaming an opponent for it.The most famous false flag operation was used by the Nazis at the start of World War Two.
The night before they invaded Poland, SS soldiers pretended to be Polish and stormed a radio tower inside Germany near the border. they broadcast a short message to say it was now in Polish hands.
Hitler used a speech the next day citing the attack as a justification for invading Poland.
Speaking on Friday, US secretary of state Anthony Blinken said: "Everything that we're seeing including what we've seen in the last 24/48 hours is part of a scenario that is already in play of creating false provocations."
Tensions have escalated to such a point the already reduced British embassy has temporarily relocated from Kyiv to Lviv in the west.
Boris Johnson will join members of the international community, including Ukrainian President Volodymyr Zelensky, at the Munich Security Conference on Saturday, but Mr Putin will remain in Russia to oversee a massive series of military drills.Several other heads of state will be there, as well as Mr Blinken.