A boy sits on a swing near his building, which was damaged during fighting between the Ukrainian army and pro-Russian separatists, as an armored personnel carrier of the Ukrainian armed forces is seen nearby in Avdeyevka near Donetsk, eastern Ukraine, June 7, 2015. REUTERS/Gleb Garanich

A member of the Right Sector's Ukrainian Volunteer Corps fires a weapon from his position during clashes with pro-Russian separatists at the Butovka coal mine near Donetsk, Ukraine, June 7, 2015. REUTERS/Oleksandr Klymenko

Members of the Right Sector's Ukrainian Volunteer Corps watch television as they rest at the Butovka coal mine near Donetsk, Ukraine, June 7, 2015. REUTERS/Oleksandr Klymenko

Members of the Right Sector's Ukrainian Volunteer Corps prepare ammunition at the Butovka coal mine near Donetsk, Ukraine, June 7, 2015. REUTERS/Oleksandr Klymenko

Members of the Right Sector's Ukrainian Volunteer Corps rest in the Butovka coal mine near Donetsk, Ukraine, June 7, 2015. REUTERS/Oleksandr Klymenko

A member of the Right Sector's Ukrainian Volunteer Corps smokes a cigarette as he rests at the Butovka coal mine near Donetsk, Ukraine, June 7, 2015.REUTERS/Oleksandr Klymenko

Members of the Right Sector's Ukrainian Volunteer Corps guard their position at the Butovka coal mine near Donetsk, Ukraine, June 7, 2015. REUTERS/Oleksandr Klymenko

A member of the Right Sector's Ukrainian Volunteer Corps walks at the Butovka coal mine damaged during clashes with pro-Russian separatists near Donetsk, Ukraine, June 7, 2015. REUTERS/Oleksandr K

Ukrainian servicemen rest at their positions located in the village of Shirokino near Mariupol, Ukraine, June 7, 2015. REUTERS/Maksim Levin

A Ukrainian serviceman stands guard at positions located in the village of Shirokino near Mariupol, Ukraine, June 6, 2015. REUTERS/Maksim Levin

A member of the Ukrainian armed forces sits at the positions located in the village of Shirokino near Mariupol, Ukraine, June 6, 2015. REUTERS/Maksim Levin

People attend a funeral of five fighters of the separatist self-proclaimed Donetsk People's Republic, who according to local residents were killed in recent battles with the Ukrainian armed forces in the town of Maryinka, at a cemetery in Donetsk, June 6, 2015. REUTERS/Alexander Ermochenko

People carry coffins as they attend a funeral of five fighters of the separatist self-proclaimed Donetsk People's Republic, who according to local residents were killed in recent battles with the Ukrainian armed forces in the town of Maryinka, at a cemetery in Donetsk, Ukraine, June 6, 2015. REUTERS/Alexander Ermochenk

A member of the Ukrainian armed forces gets down a trench located near the town of Horlivka, north of Donetsk, Ukraine, June 6, 2015. REUTERS/Oleksandr Klymenko

Members of the Ukrainian armed forces gather at their positions located near the town of Horlivka, north of Donetsk, Ukraine, June 6, 2015. REUTERS/Oleksandr Klymenko