UNDISCLOSED: Ukrainian soldiers frowned as they pored over a small device plugged into a computer — a drone interceptor captured from the Russian side. The green device with a dome-shaped nose and 30-centimeter wingspan epitomises the technological arms race playing out between Kyiv and Moscow as their troops battle on the sprawling front line. Deployed in their hundreds by both sides every day, drones have become the chief technology of the war, scouting out enemy positions and packed with explosives to crash down into soldiers, vehicles and equipment.