Ukraine's President Poroshenko vows to act over deaths
12 July 2014 Last updated at 10:01 BST
The President of Ukraine, Petro Poroshenko, says his forces will find and destroy pro-Russian separatists who killed more than 20 Ukrainian troops in the east of the country.
The attack on government forces appears to be the most deadly since Mr Poroshenko ended a unilateral ceasefire last month.
Emily Thomas reports.