The White House says the U.S. government is still trying to determine who was responsible for Sunday's deadly shootout in eastern Ukraine and did not specify when Russia would have to meet the terms of a Geneva agreement for containing tensions in the former Soviet state.
White House spokesman Jay Carney said pro-Russian militants in eastern Ukraine must lay down their arms and abandon occupied buildings. He said Russia has influence over Ukrainian separatists and warned Moscow to live up to commitments last week to help stabilize the conflict or risk further sanctions.
Carney offered no timeline that would trigger those sanctions.
He said the U.S. could not independently assess blame for the shootout Sunday that left at least three dead. Russian and Ukrainian officials traded blame for the attack.