U.S. Vice President Joe Biden has arrived in Kyiv for talks with Ukraine's acting president and prime minister. His visit comes as the situation in eastern Ukraine remains tense, despite a deal aimed at easing the crisis.
White House officials say Biden will discuss 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.
An Easter Sunday truce barely lasted 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 blames the attack on Russian special forces. But Russian Foreign Minister Sergei Lavrov accuses the Ukrainian government of not wanting to control extremists who he says 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.