Fedorov's office sports a huge video screen with dozens of live feeds from Ukrainian drones flying over the front lines. Together, the feeds provide a vivid glimpse into Ukraine's drone war, in which commanders claim flying robots now account for an estimated 70% of all Russian deaths and injuries.

Russian air defenses destroyed 73 Ukrainian drones overnight, including three heading for Moscow, Russia's defence ministry said on Friday.

They're cheap, they're deadly and they're among the main reasons Ukraine believes it can hold out against advancing Russian forces this year and even beyond, according to a dozen Ukrainian commanders,