Russian forces battled Ukrainian troops for a third day on Thursday, after Ukraine smashed through the border in the Kursk region and forced Moscow to call in reserves. In one of the biggest Ukrainian attacks on Russia of the two-year-old war, around 1,000 Ukrainian troops rammed through the Russian border in the early hours of Aug. 6 with tanks and armoured vehicles, covered in the air by swarms of drones and pounding artillery, according to Russian officials.