Russia's point man for relations with the United States said on Monday that all of President Vladimir Putin's conditions must be met in full before the war in Ukraine can end, suggesting Moscow is playing hardball with U.S. President Donald Trump.

Russia's foreign minister drove the point home, saying that while Moscow was ready for talks with Ukraine, results could be achieved only if the "fundamental reasons" behind the nearly three-year-old conflict were resolved.

Trump, who has repeatedly said he wants to end the war in Ukraine swiftly, after hundreds of thousands of deaths, said on Sunday he thought he was making progress, though he has not set out how he hopes to end the conflict.