US President Barack Obama and Russian President Vladimir Putin spoke by telephone on Wednesday, discussing crises in Ukraine and Syria, the White House said.
"They spent a significant portion of their time discussing the need for the Russians to live up to the commitments that they made in Minsk -- to end their support for separatists that are destabilizing Ukraine right now," said White House spokesman Josh Earnest.
Ukraine and pro-Russian rebels agreed a new truce deal Wednesday that goes into immediate effect and replaces one broken just hours after its signature at the end of last month.
Kiev's pro-Western leaders and the insurgents are fighting over an industrial region the approximate size of Wales that is home to about 3.5 million people and the center of the splintered former Soviet nation's coal and steel wealth.
Russia firmly denies allegations of orchestrating and backing the war in order to keep some leverage over Ukraine in the wake of its decision to establish closer trade and political relations with the European Union.
Earnest also said that Obama and Putin have also discussed ongoing efforts to end Syria's brutal civil war.
They discussed the "effort to try to bring about a political transition inside of Syria."
"Both the United States and Russia have a vested interest in seeing that occur."