"We believe Russia will target Ukraine's capital Kyiv," U.S. President Joe Biden said in a press conference late Friday.
Biden also said that a major uptick of cease-fire violations by Russia has been observed in the last days.
"U.S. and allies remain united despite Russia's attempts to divide," he added.
Biden also said that he's “convinced” that Russian President Vladimir Putin has decided to launch a further invasion in Ukraine, saying he has “reason to believe” it will occur in the “coming days” and will include an assault on Kyiv.
After weeks of saying the U.S. wasn't sure if Putin had made the final decision to launch a widespread invasion, Biden said that assessment had changed.
“As of this moment I’m convinced he’s made the decision," Biden said.
"We have reason to believe that.”
He cited the United States’ “significant intelligence capability" for the assessment.
Biden reiterated his threat of massive economic and diplomatic sanctions against Russia if it does invade, and pressed Putin to rethink his course of action. He said the U.S. and its Western allies were more united than ever to ensure Russia pays a price for the invasion.
Earlier on Friday, U.S. Secretary of State Antony Blinken said Russia's claims it was pulling forces back from the border are false, adding that "on the contrary, we see additional forces going to the border including leading edge forces that would be part of any aggression."
Blinken also said that everything Washington has seen happening on Russia's border with Ukraine in the past 24 to 48 hours is part of a scenario of creating false provocations designed to elicit a response.
On Wednesday, the White House warned that Russia could invade Ukraine at any time using a fabricated pretext or a false flag operation.
"We're in the window where we believe an attack could come at any time and that would be preceded by a fabricated pretext that the Russians use as an excuse to launch an invasion," White House press secretary Jen Psaki said at a news conference. "And we've seen and we've talked about this a bit in here. We've seen these tactics used in the past."
Washington has estimated that some 30,000 Russian troops have been deployed at neighboring Belarus as part of joint exercises that are due to run until Sunday.
Those drills as well as other large-scale exercises near Ukraine have fueled concerns in European capitals and Washington that Moscow is preparing an attack on its neighbor.
Russia has denied any plans and accused Ukraine of breaching cease-fire agreements in the east of the country, where the army is fighting pro-Moscow separatists.