In Ukraine's eastern Donetsk region, soldier Mykola shows off his drone signal jamming system: It may look like just a large white thermos, but it serves as a crucial shield for both sides in the war.

Scramblers have become a mainstay in recent months in Ukraine, used to neutralize the little killer drones that now saturate the sky over battlefields.

More than two years into Russia's invasion, the devices have become essential for Ukrainian forces.