Joe Biden has announced the first US sanctions against Russia as he confirmed Vladimir Putin's actions constituted "the beginning of a Russian invasion of Ukraine".
The US President added during a White House press conference today: "If Russia goes further with this invasion, we stand prepared to go further with our sanctions."
He stated that Putin was "carving out a big chunk of Ukraine", which he emphasised had broken the law.
Biden said: "This is the start of the invasion of Ukraine.
"What in the name of the lord gives [Putin] the right to declare new so-called countries on territory that belongs to his neighbours? He's setting up to take more territory by force.
"In response to Russia's admission that it will not withdraw its forces from Belarus, I have authorised additional movements of US forces and equipment already stationed in Europe to strengthen our Baltic allies - Estonia, Latvia and Lithuania.
"Let me be clear, these are totally defensive moves on our part. We have no intention of fighting Russia.
"We want to send an unmistakable message though, that the United States together with our allies will defend every inch of Nato territory and abide by the commitments we made into Nato.
"We still believe Russia is poised to go much further. I hope I'm wrong about that.
"We will put sanctions which go far beyond 2014."
The president warned the actions could hurt people financially back home - especially at petrol pumps.
Threatened sanctions against the Kremlin include targeting Russian banks and sovereign debt meaning it cannot raise money from the West.
Biden warned even steeper sanctions will follow if it continues to be aggressive towards Ukraine.
He added: "There are still well over 150,000 Russian troops surrounding Ukraine, and as I said, Russian forces remain positioned to Belarus to attack Ukraine from the north, including warplanes and offensive missile systems.
"Russia's naval vessels are manoeuvring in the Black Sea to Ukraine's south including amphibious assault ships, missile cruisers, and submarines.
"Russia has moved supplies of blood and medical equipment into position on their border. You don't need blood unless you plan on starting a war."
It comes after the White House admitted it is now describing the movement of Russian troops into rebel-held areas of Ukraine as an invasion by Moscow.
Jon Finer, principal deputy national security adviser, said: “We think this is, yes, the beginning of an invasion, Russia's latest invasion into Ukraine.
"An invasion is an invasion and that is what is under way."
The world has been braced for the move for weeks after around 150,000 Russian troops were massed on the borders of Ukraine.
Last night in a lengthy speech, Putin recognised the independence of two Russian-backed rebel regions, Donetsk and Luhansk, and dispatched troops to perform “peace-keeping duties”.
As he was talking, President Biden was on the phone with Ukraine's President Volodymyr Zelenskyy.
He had earlier spoken to German Chancellor Olaf Scholz and French President Emmanel Macron.
Last week Biden warned the US had “reason to believe” Russia would invade soon, adding: “My sense is that it will happen within the next several days.”
When asked if he planned on calling the Russian president he replied: “I'm not calling — I have no plans to call Putin.”
Earlier this month, as he urged Americans to leave Ukraine before it was too late, he warned the situation in the country could become “crazy” very quickly.
This afternoon Putin requested - and was granted - permission to use armed forces abroad sparking fears of a full scale attack on its neighbour.
In Brussels NATO Secretary-General Jens Stoltenberg said it was “never too late to not attack.”
He added: “Every indication is that Russia continues to plan for a full scale attack on Ukraine. We see the ongoing military build up... We see that more and more of the forces are moving out of the camps and are in combat formations and ready to strike.
"And we see the ongoing provocations in Donbas and the different false flag operations where they tried to create a pretext for an attack. And then of course we saw last night that further Russian troops moved into Donbas, into parts of Donetsk and Luhansk.
"And then we have the threatening rhetoric, which was actually confirmed in the speech of President Putin yesterday.
"At the same time, it's never too late. It's never too late to not attack. And that's the reason why we continue to call on Russia to step back, to de-escalate, and to engage in good faith in diplomatic efforts to find a political solution."
