Small, maneuverable and impossible to jam, Russia’s best fiber-optic drones can—in the hands of skilled operators—slip into the buildings and dugouts sheltering Ukrainian vehicles. A video circulated by Russian sources on or before Monday depicts a warhead-laden quadcopter drone easing under a tarp and into a barn where a Ukrainian Bohdana wheeled howitzer was parked.

According to a Nato official, more than two thirds of the Russian tanks that Ukraine’s military has destroyed in the first half of last year have been taken out using first-person view (FPV) drones, while a large portion of Russia’s Black Sea fleet has reportedly been obliterated by airborne drones.