Kerry spoke with Russian Foreign Minister Sergei Lavrov by telephone on Monday morning, State Department spokeswoman Jen Psaki said. Russia, Ukraine, the European Union and the United States on Thursday agreed on ways to ease tensions in the worst confrontation between Russia and the West since the Cold War.
"The secretary urged Russia to take concrete steps to help implement the Geneva agreement, including publicly calling on separatists to vacate illegal buildings and checkpoints, accept amnesty and address their grievances politically," Psaki said at a news briefing.
With pro-Moscow separatists showing no sign of surrendering government buildings they have seized in eastern Ukraine, Washington pegged a threat of new sanctions on Russia to how hard Moscow tries to make the Geneva agreement work.
The Geneva agreement calls for illegally occupied buildings to be vacated under the auspices of envoys from the Organization for Security and Cooperation in Europe.
Kerry called on Russia to assign a senior diplomat to work with the OSCE mission in eastern Ukraine, Psaki said, "to make absolutely clear to the separatists that Russia supports the agreement and wants de-escalation."
Kerry told Lavrov the government of Ukraine sent senior representatives to the east with the OSCE, put forth a broad amnesty bill for separatists to give up buildings and weapons and called an Easter pause in its military operations.
U.S. and European officials say they will hold Moscow responsible and impose new economic sanctions if the separatists do not clear out of government buildings they have occupied across swathes of eastern Ukraine over the past two weeks.