U.S. Vice President Joe Biden has offered condolences to Ukrainian President Petro Poroshenko over killings in eastern Ukraine.
At last four people were killed by artillery fire in an overnight attack on July 12 in Maryinka, a suburb of Donetsk where pro-Russia insurgents are holed up.
The attack happened hours after Poroshenko vowed vengeance for the deaths of 19 troops in an insurgent rocket attack near the Russian border.
During their second conversation this week, the White House says Biden also expressed support for Poroshenko's efforts to convene a meeting with the separatists on a possible new cease-fire.
Biden also briefed Poroshenko on efforts by the United States and its allies to punish Russia if it continues to provide the insurgents with heavy weapons and equipment.
Meanwhile, Poroshenko will not attend the final of the World Cup in Brazil.
His office said Poroshenko had decided it was "impossible" to attend the game due to the "current situation in Ukraine."
Earlier, the Brazilian government said that Poroshenko had accepted an invitation to attend the final between Germany and Argentina in Rio de Janeiro.
There had been hopes Poroshenko could have met Russian President Vladimir Putin at the game with the possibility of talks on the crisis in eastern Ukraine.
Based on reporting by AP and AFP