Russian President Vladimir Putin called U.S. President Barack Obama to discuss continued tensions in eastern Ukraine and various areas of concern in the Middle East.
The White House said Obama told his Russian counterpart that he needs to remove all "troops and equipment" from Ukrainian territory.
The call came on the same day NATO's supreme allied commander cited a continuous flow of ammunition and other military supplies from Russia across the border to Ukraine.
Putin, who has consistently denied backing the pro-Russian rebels in Ukraine, initiated the phone call Thursday.
The two leaders also addressed continued bloodshed in Syria, where the self-proclaimed Islamic State group has made rapid gains, and agreed on the importance of unity among the six world powers that are negotiating to restrict Iran's nuclear capabilities.
Reuters reports it was the first phone conversation between the two leaders since February.
Some information for this report provided by AP, Reuters.