U.S. President Donald Trump spoke to Russia's Vladimir Putin on Monday about peace in Ukraine after Washington said there was an impasse over ending Europe's deadliest conflict since World War Two and that the United States may have to walk away.

Trump expressed his hopes for a “productive day” Monday — and a ceasefire — in a social media post over the weekend. His effort will also include calls to NATO leaders. But ahead of the call, Vice President JD Vance said Trump is “more than open” to walking away from trying to end the war if he feels Putin isn't serious about negotiation.

A telephone call between the two leaders would be the latest chapter in a flurry of diplomatic maneuvering over ending the three-year conflict.