"We continue to see signs of Russian escalation, including the arrival of new forces on the Ukrainian border," White House National Security Adviser Jake Sullivan warned after US President Joe Biden's virtual meeting with its main Western counterparts.
"An invasion could occur at any time if Vladimir Putin gives the order," he added.
"It could start during the Olympics, despite all the speculation that it will only come after the Games," he said.
According to him, such an offensive is a “very, very real possibility”, but American intelligence does not know whether the Russian president “has made a final decision” or not.
The United States, United Kingdom, Australia and Germany have urged their nationals to leave Ukraine as soon as possible.
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In Chernobyl, Ukrainian forces prepare for a possible Russian invasion
Some 3,000 more American soldiers will be ready in Poland “in the coming days”, also announced another senior American official.
President Biden could thus speak on the telephone soon with his Russian counterpart.
French Head of State Emmanuel Macron spoke with Vladimir Putin this Saturday noon, according to the Elysee Palace, before a visit to Moscow by German Chancellor Olaf Scholz early next week.
Western leaders met on Friday afternoon as European diplomatic efforts bog down to try to prevent the Russian-Western crisis around that country from escalating into war.
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