U.S. Secretary of State John Kerry has urged Russia to take "concrete steps" to implement an agreement aimed at defusing tensions in Ukraine.
Kerry told Russian Foreign Minister Sergei Lavrov by telephone Monday that the steps Russian should take include "publicly calling on separatists to vacate illegal buildings and checkpoints, accept amnesty, and address their grievances politically." Those steps were part of an agreement reached April 17 between top diplomats from Ukraine, Russia, the European Union and the United States on easing tensions in eastern Ukraine.
A State Department spokeswoman quoted Kerry while briefing reporters in Washington.
Earlier Monday, U.S. Vice President Joe Biden arrived in Kyiv for talks with Ukraine's acting President Oleksandr Turchynov and acting Prime Minister Arseniy Yatsenyuk. His visit comes as the situation in eastern Ukraine remains tense, despite a deal aimed at easing the crisis.
White House officials say Biden's meetings on Tuesday will focus on the international community's efforts to help Ukraine move forward on constitutional reform and what Obama administration officials say will be a free and fair presidential election on May 25.
In addition to Mr. Turchynov and Mr. Yatsenyuk, Biden is expected to meet with Ukrainian lawmakers, sending a high-level message of U.S. support for the current Ukrainian government. The United States has threatened further sanctions on Russia if Moscow continues its support of pro-Russian demonstrators in eastern Ukraine.
Russia's Foreign Ministry, for its part, said Lavrov stressed in his phone conversation with Kerry what it described as Kyiv's "inability and unwillingness" to halt violence by the Right Sector group and other "ultra-nationalists" or to end arrests of pro-Russian activists, which it said are threatening the April 17 agreement.
The ministry said Lavrov urged Kerry to influence Kyiv not to let "hotheads there provoke a bloody conflict" and impel the Ukrainian authorities to fulfill their obligations "rigorously."
An Easter Sunday truce lasted barely a few hours before it was shattered by a gunfight at a checkpoint in the pro-Russian eastern city of Slavyansk. Three people were killed. It is not clear exactly what happened.
Ukraine blamed the attack on Russian special forces. But Russian Foreign Minister Sergei Lavrov accused the Ukrainian government of not wanting to control extremists who he said are shooting unarmed civilians.
Lavrov said Monday Ukraine is "crudely" violating last week's Geneva agreement calling on all armed illegal groups in the east to disarm and leave. The agreement also calls for a mission by European monitors.
However, pro-Russian demonstrators who have taken over government buildings in about a dozen eastern Ukrainian cities have so far showed no sign of backing down.
Lavrov said the United States must recognize its responsibility for the crisis in Ukraine through its support of the new Ukrainian government.
He said attempts to isolate Russia through sanctions will fail, saying the majority of the world does not want to isolate Russia.
The pro-Russian demonstrators in Ukraine are demanding the right to hold referendums on splitting with Ukraine and joining with Russia. A vote last month in Crimea led to the Russian annexation of the Ukrainian peninsula.