Russia's Foreign Minister Sergei Lavrov has called for "urgent measures for preventing an impending humanitarian catastrophe" in Ukraine during a telephone call with US counterpart John Kerry, his department says.
A statement from the Russian Foreign Ministry said Kerry "confirmed such work is being carried out with the Kiev authorities".
The statement follows reports that Ukrainian forces had surrounded the rebel-held city of Donetsk in the east of the country.
More top news
Ross Brennan, 28, conspired with Aarron Gledhill, 30, to import and sell powerful class A drugs to thousands of customers.
Pyongyang's foreign minister said Donald Trump's aggressive rhetoric is regarded as a legitimate "declaration of war".
Former congressman Anthony Weiner has been jailed over an underage sexting scandal which helped rock Hillary Clinton's election campaign.