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US President Joe Biden on Friday said he is convinced Russia will invade Ukraine and that Moscow plans to push an offensive all the way to the capital Kiev, home to about three million people.
Speaking from the White House, Mr Biden outlined what he saw as the likely start of what could become the gravest confrontation Europe has seen since the Second World War.
“We have reason to believe the Russian forces are planning to intend to attack Ukraine, in the coming week, the coming days,” Mr Biden said. He added that Moscow is likely to “target Ukraine's capital Kiev, a city of 2.8 million innocent people".
He said that, “as of this moment, I'm convinced [Russian President Vladimir Putin has] made the decision” to launch an invasion.
Moscow has already launched an information war to justify an invasion, the president said, noting that Russia is creating “more and more disinformation” that was being sent to the Russian public, including claims that Ukraine is planning to launch an offensive attack in the eastern Donbas region.
“It defies basic logic to believe the Ukrainians would choose this moment, with well over 150,000 troops arrayed on its borders, to escalate,” he said.
Ukraine's foreign ministry pre-emptively denied it had any attack plans.
Mr Biden's remarks came at the end of an extremely tense day in eastern Ukraine, where a series of explosions rocked the Donbas region.
Separatists in the Donbas cities of Luhansk and Donetsk said they were moving civilians to Russia.
The announcement appeared to be part of Moscow’s efforts to counter western warnings of a Russian invasion and to paint Ukraine as the aggressor instead.
To that end, Moscow pointed to a bombing that struck a car outside the main government building in Donetsk. The head of the separatists’ forces, Denis Sinenkov, said the car was his, the Interfax news agency reported. He was unhurt.
While shelling and shooting are common along the line separating Ukrainian forces and the rebels, targeted violence is unusual in rebel-held cities like Donetsk.
However, the explosion and the evacuations were in line with US warnings of false flag attacks.
Compounding the volatility, Russian media reported another explosion in Luhansk and a blast at a nearby gas pipeline.
White House Press Secretary Jen Psaki said the US had long predicted “the Russians would take part in pretext or steps that would lay a predicate for either war or to create confusion or spread misinformation on the ground about what's actually happening".
Mr Putin on Saturday was scheduled to oversee Russian exercises involving its strategic nuclear forces.
He will observe the drills involving practice launches of intercontinental ballistic missiles and cruise missiles in a demonstration showing that Russia remains a nuclear superpower.
Mr Biden said he does not think Mr Putin is “remotely contemplating” using nuclear weapons.
“He is focused on trying to convince the world that he has the ability to change the dynamics in Europe in a way that he cannot,” the US president said.
His remarks came shortly after he spoke with leaders from Canada, Europe and Nato.
A US official said Russia was behind this week's cyber attacks on the Ukrainian defence ministry and major banks.
The announcement from Anne Neuberger, the White House’s chief cyber official, was the most pointed attribution of responsibility for cyber intrusions that have unfolded as tension escalates between Russia and Ukraine.
She said that while the attacks had a limited impact, they “are consistent with what a Russian effort could look like” and there could be more destructive cyber attacks if Russia proceeds with a further invasion of Ukraine.
“We've been preparing for this responsibility,” she said.
The official said the world must be prepared to “shine a light on malicious cyber activity” and hold actors accountable for attacks.
There are no credible or specific cyber threats to the US at this time, Ms Neuberger added.
At least 10 websites for Ukrainian government agencies and banks were hit with cyber attacks on Tuesday amid growing fears that Russia was preparing to invade the country.
Those websites included the Defence Ministry, Foreign Ministry, Culture Ministry and Ukraine’s two largest state banks.
Speaking alongside Ms Neuberger at the White House, Daleep Singh, the deputy US national security adviser for international economics, said an invasion of Ukraine would mean a “strategic defeat for Russia, pure and simple".
“If Russia invades Ukraine, it would become a pariah to the international community,” Mr Singh said.
“It will become isolated from global financial markets and be deprived of the most sophisticated technological inputs.”
He predicted “intense capital outflows, mounting pressure on its currency, surging inflation, higher borrowing costs, economic contraction and the erosion of its productive capacity".
Meanwhile, Vice President Kamala Harris has travelled to Germany for the Munich Security Conference, as she leads the US delegation in crisis talks on Ukraine.
Ms Harris is expected to address the conference on Saturday.
Agencies contributed to this report