U.S. President Donald Trump has hinted that Washington may "take a pass" on brokering a peace deal in the Russia-Ukraine war, putting pressure on both Moscow and Kyiv as negotiations continue with little progress.

Speaking at the Oval Office on Friday, Trump said although the U.S. would ideally like to see the war come to an end, if either side "makes it very difficult," Washington may "just take a pass."

Trump added that he isn't expecting a truce to happen in "a specific number of days," but that he wanted it done "quickly."

Earlier, U.S. Secretary of State Marco Rubio said the U.S. plans to decide within days whether a peace deal is realistically possible.

Rubio also emphasized that the U.S. had "other priorities to focus on," and if it becomes clear the deal won't happen, Washington will move on.

Before taking office in January, Trump had pledged to end the war in Ukraine within the first 24 hours of his presidency.