Ukrainian president thanks Biden for 'unprecedented' U.S. support, following 'minor incursion' gaffe

Ukrainian President Volodymyr Zelensky on Friday applauded President Biden for reaffirming his support for his country if Russia decides to invade.

The leader tweeted: "Thank you @POTUS for the unprecedented diplomatic and military assistance."

Zelensky was responding to comments Biden made clarifying the position of the United States, should Russia invade. 

"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," said the president Thursday. "Let there be no doubt at all that if Putin makes this choice, Russia will pay a heavy price."

The comments came one day after Biden made some confusing remarks about what a "minor incursion" would yield during a press conference marking one year of his presidency. 

Following Biden's initial comments, which members of the administration were forced to immediately walk back, Zelensky tweeted: "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."

The U.S. and other allies have promised heavy sanctions against Moscow, should Putin opt to invade Ukraine. Russia has said it will not move any of its 100,000 troops that are currently amassed at the Ukrainian border until NATO agrees not to, ever, accept Ukraine as a member nation. The White House has made it clear that it will not agree to that term.