Ukrainian President Petro Poroshenko has vowed to take revenge on pro-Russian separatists after dozens of government troops were killed in a rocket attack. Renewed fighting between the 2 sides has dampened hopes for a ceasefire.
Government forces have intensified their military operations in eastern Ukraine and retaken separatist strongholds in Slaviansk and Kramatorsk in the Donetsk region.
The separatists fought back with a rocket attack in the Luhansk region, near the Russian border.
Ukraine's defense ministry says 23 soldiers were killed and 93 injured on Friday.
Poroshenko convened an emergency meeting of his security chiefs and vowed to strike back.
He said for every Ukrainian soldier killed, the separatists will pay with tens and hundreds of their own. He said none of the "terrorists" will evade responsibility.
Although France and Germany are urging Russia to mediate a truce, separatists have refused to negotiate with the government and have vowed to continue fighting.
Jul. 12, 2014 - Updated 01:12 UTC