Ukraine's President Volodymyr Zelensky told Fox News late on Tuesday that Ukraine would lose the war if Washington, its main military backer, pulled funding.
The Ukranian leader said it would be "very dangerous if we lose unity in Europe, and what is most important is unity between Ukraine and the United States".
US President-elect Donald Trump has campaigned on a promise to end US involvement in wars and instead use taxpayers' money to improve Americans' lives.
He has said he will bring the Russia-Ukraine war to an end within 24 hours, without saying how.