Ukrainian president praises Biden for reaffirming US support

Ukrainian President Volodymyr Zelensky praised President Biden on Friday for reaffirming his support for Ukraine if Russia invades.

"Thank you @POTUS for the unprecedented diplomatic and military assistance," Zelensky tweeted.

The tweet was in response to a speech Biden made to clarify the United States' support for Kyiv as Russia amasses troops on its border with Ukraine.

"I've been absolutely clear with President Putin. He has no misunderstanding. If any assembled Russian units move across the Ukrainian border, that is an invasion," Biden said Thursday at an infrastructure event, referring to Russian President Vladimir Putin.

"Let there be no doubt at all that if Putin makes this choice, Russia will pay a heavy price," Biden added.

Biden and other allies have promised heavy sanctions against Russia in the event of an attack, and Russia has said they won't send troops away from the border until NATO agrees not to accept Ukraine into the alliance and withdraws its weapons in Eastern Europe.

The White House and Biden sought to clear up remarks the president made at a Wednesday press conference that suggested the U.S. would not respond as forcefully to a "minor incursion" by Russia against Ukraine.

"I think what you're going to see is that Russia will be held accountable if it invades. And it depends on what it does. It's one thing if it's a minor incursion and then we end up having a fight about what to do and not do," Biden said at the time.

Zelensky fired back at Biden's comment on Twitter, saying, "We want to remind the great powers that there are no minor incursions and small nations. Just as there are no minor casualties and little grief from the loss of loved ones. I say this as the President of a great power."