US President Joe Biden on Wednesday predicted Russia "will move in" to Ukraine, citing existential concerns by the country's president, Vladimir Putin, even as he acknowledged disunity within NATO over how to respond to a "minor incursion."

The candid assessment laid bare the struggle Biden faces in creating meaningful consequences and deterrents for Moscow, which remains closely intertwined economically with the United States' top European partners.

The remark elicited near-immediate outcry in Kyiv, where officials have been meeting with Biden's top diplomat as Russian troops amass on the country's border. High-level attempts to clean-up the comment soon followed at the White House.

While Biden vowed withering economic consequences on Russia should Putin send his troops over the frontier, including restricting its financial transitions in US dollars, he suggested Western nations were not in sync on what to do should a lesser violation occur.

"It's one thing if it's a minor incursion and we end up having to fight about what to do and not do," Biden told reporters at an East Room news conference. "But if they actually do what they're capable of doing with the forces amassed on the border, it is going to be a disaster for Russia if they further invade Ukraine."

Later, asked to clarify what he meant by "minor incursion," Biden said he drew the line at "Russian forces crossing the border, killing Ukrainian fighters"

"I think that changes everything," the President said. "But it depends on what he does, to what extent we'll get total unity on the NATO front."

"It's very important that we keep everyone in NATO on the same page. That's what I'm spending a lot of time doing, and there are differences," he went on. "There are differences in NATO as to what countries are willing to do, depending on what happens."

The candid assessment of NATO's divisions -- which have been well documented, even as US and Western officials seek to project unity amid the crisis -- left Ukrainian officials aghast. One told CNN's Matthew Chance he was "shocked that the US President Biden would distinguish between incursion and invasion" and suggested that a minor incursion would not trigger sanctions.

"This gives the green light to Putin to enter Ukraine at his pleasure," the official added, claiming he'd never heard any nuance like this from the US administration before.
"Kyiv is stunned," he said, referring to the Ukrainian government.

The White House sought to explain Biden's remarks by pointing out a Russian attack in cyberspace or through paramilitary forces would prompt a reciprocal response compared to a scenario where Russian troops move from their positions into Ukraine.

"President Biden has been clear with the Russian President: If any Russian military forces move across the Ukrainian border, that's a renewed invasion, and it will be met with a swift, severe, and united response from the United States and our Allies," press secretary Jen Psaki wrote in a statement following Biden's marathon news conference.

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"President Biden also knows from long experience that the Russians have an extensive playbook of aggression short of military action, including cyberattacks and paramilitary tactics," Psaki went on. "And he affirmed today that those acts of Russian aggression will be met with a decisive, reciprocal, and united response."

A senior administration official said if Russian military forces tried to take Ukrainian territory by force and violated Ukrainian sovereignty -- whether that was a "small portion or a large portion" of land -- that would constitute an "invasion" by the Biden administration's standards and would warrant severe penalties.

And while the official acknowledged the US and NATO members likely will not have the "same list" of targets and details matching on every measure, the response would remain "highly unified" and "provide a force multiplier to actions we take."

Biden's remarks came as the US entered what officials have deemed a dangerous period, when a Russian invasion could occur at any moment. The President, while acknowledging lingering uncertainty over Putin's intentions, said Wednesday he believed the Russian leader would soon invade Ukraine.

"I'm not so sure he is certain what he is going to do. My guess is he will move in. He has to do something," Biden said, describing a leader searching for relevance in a post-Soviet world. "He is trying to find his place in the world between China and the west."

Biden's prediction of an invasion was the firmest acknowledgment to date the United States fully expects Putin to move after amassing 100,000 troops along the Ukraine border.

After speaking with Putin twice last month, Biden said he believed his Russian counterpart had a good understanding of the economic sanctions he was preparing to enact.

"He's never seen sanctions like the ones I promised will be imposed if he moves, number one," he said, adding the level of punishment would depend on what Russia's invasion looks like.

That includes limiting Russian transactions in US financial institutions - "anything that involves dollar denominations," Biden said.

The President warned Russian lives would be lost in an invasion, along with potential Ukrainian casualties.

"The cost of going into Ukraine in terms of physical loss of life for the Russians -- they'll be able to prevail over time but it's going to be heavy," he said. "It's going to be real. It's going to be consequential. Putin has a stark choice. Either de-escalation or diplomacy. Confrontation and consequences."

"This is not all just a cake walk for Russia," he went on. "Militarily, they have overwhelming superiority. And as it relates to Ukraine, they'll pay a stiff price immediately, near term, medium term and long term if they do it."

Biden speculated Putin was not seeking "any full-blown war," but said he did believe he was looking for some type of confrontation: "Do I think he'll test the west? Test the United States and NATO as significantly as he can? Yes, I think he will. But I think he'll pay a serious and dear price for it."

Biden's prediction came after Ukrainian President Volodymyr Zelensky on Wednesday urged Ukrainians to not panic and to "calm down" over fears of a possible Russian invasion.

"All our citizens, especially the elderly, need to understand this: Everyone needs to exhale. Calm down. Don't run for emergency supplies like buckwheat and matches. To all the media: Remain as the media, not become a source of mass hysteria. Do not help the enemy in the pursuit of hype by reporting daily that war may happen tomorrow! This will definitely not stop it."

"What is new here? Is this not the reality for the past eight years? Didn't the invasion begin in 2014? Did the threat of the war emerge just now?" he said.

The only reason for "panic is that after eight years we are still influenced by this panic," he added.

Zelensky said Russia's "aim is to weaken Ukraine" in order to force Kyiv to concede to Moscow and "to create such a background that our 'no' sounds weaker."

The Ukrainian leader said Moscow is "actively attacking your nerves, not our state. So that you have a constant feeling of panic."

This story and its headline have been updated with additional reporting Wednesday. -CNN