Ukraine war latest: Ukrainian forces control 60% of Vovchansk; heavy battles continue in Kharkiv Oblast
Key developments on May 20: * Deputy governor: Ukraine controls around 60% of Vovchansk * General Staff: Ukraine fights off Russian attack near Starytsia village in Kharkiv Oblast * Governor: Ukraine strikes Russian base in occupied Luhansk Oblast * Russian media: Oil refinery in Russia's Krasnodar Krai damaged after drone attack * Estonian PM: NATO