Ukraine's deadliest clashes
 24 April: Ukraine military kills five rebels in assault on Sloviansk
2 May: More than 40 people killed in burning building after street fighting in Odessa
 9 May: 20 pro-Russian activists and Ukrainian security officer killed in Mariupol
13 May: Seven Ukrainian soldiers killed in ambush between Sloviansk and Kramatorsk
 22 May: Rebel attack on checkpoint in Volnovakha leaves at least 14 soldiers dead
27 May: At least 40 rebels killed in "anti-terrorist operation" against separatists holding Donetsk airport
29 May: Ukrainian military helicopter shot down near Sloviansk, killing 14