In a series of responses to questions during his first press conference during 2022, Mr Biden said he believed the Russian leader did not want “a full-blown war”.
Yet, he suggested that Mr Putin might be happy for a “minor incursion”.
“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.”
He later clarified he considered a “minor incursion” something such as a cyber attack, rather than the use of his military.
“Do I think he’ll test the West? Test the United States and Nato as significantly as he can,” he said. “Yes, I think he will.”
Yet, his admission that Ukraine will not be admitted membership of Nato “anytime soon”, was seized on by critics as an encouragement to Moscow. So too was Mr Biden’s apparent admission Mr Putin may feel obliged to act.
Ari Fleischer, who was George W Bush’s first White House press secretary, tweeted: “Biden just told Putin a ‘minor incursion’ into Ukraine is basically ok. What kind of answer was that? No incursion is ok.”
Mr Biden has insisted if Russia did invade Ukraine, as it did Crimea in 2014, it would pay a “dear price”.
At one point during a press conference that lasted a little over 1 hour and 50 minutes, he paused as he pondered over what Mr Putin might do, suggesting he was constrained by speaking in a “public forum”.
“I think he is dealing with what I believe he thinks is the most tragic thing that’s happened to Russia - in that the Berlin Wall came down, the empire has been lost, the Soviet Union has been split,” he said,
He said Mr Putin had indicated to him he wanted a guarantee that Ukraine not be permitted to join Nato, and that strategic nuclear weapons not be placed there.
On the issue of Ukraine’s membership of Nato, he said it was “unlikely” to happen soon.
He also said it was possible the US and Russia could reach agreement over the positioning of nuclear weapons in Ukraine, depending on what Mr Putin did along its border. He added the US was planing to push more troops into places such as Poland and Romania.
“Think about what he has. He’s eight timezones, burning tundra, that will not freeze again naturally. A situation where he has a lot of oil and gas, but he has tried to find his place in the world between China and the West,” he said.
“And so I’m not so sure that he ... is certain what he’s going to do. My guess is he will move in. He has to do something.”
Mr Biden’s comments came hours after US Secretary of State Antony Blinken during a visit to Kyiv, accused Russia of planning to reinforce the more than 100,000 troops it has deployed along the Ukrainian border and suggested that number could double “on relatively short order.”
Mr Blinken did not elaborate, but Russia has sent an unspecified number of troops from the country’s far east to its ally Belarus, which also shares a border with Ukraine, for major war games next month.
The US president said he believed the decision would “solely” be Mr Putin’s and suggested he was not fully confident that Russian officials with whom top White House advisers have been negotiating are fully informed about the Russian leader’s thinking.
“There’s a question of whether the people they’re talking to know what he’s going to do,” Mr Biden said.
The White House later issued a statement that sought to draw a line under any uncertainty that the president might have created.
“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,” it said. “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. And he affirmed today that those acts of Russian aggression will be met with a decisive, reciprocal, and united response.”
Additional reporting by Associated Press
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