They are fishing nets, but they are not catching fish. They are catching Russian drones.

The nets are strung over roads leading to hot spots in Ukraine’s eastern front, above military checkpoints and artillery positions. They are sewn in cities far from the front, or shipped from Nordic ports, donated by fishermen who no longer need them.

Their purpose is to thwart the Russian drones that now swarm the skies above the front lines and swoop in on practically anything that moves, whether it is an armored vehicle racing to resupply troops or a soldier hiding in a tree line.

With their dense mesh, the nets can tangle drone propellers and immobilize the weapons. They are a simple but effective countermeasure against drones that are often too fast to shoot down and can fly deep behind the front to strike logistical routes once out of reach.

Russia has also increasingly used drones connected by fiber-optic cables rather than ones that rely on electronic signals. The cables make them immune to jamming, a standard method used to counter drones on the battlefield. The nets have become one of the few remaining ways to catch drones before they hit.

“Military engineers noticed that even an ordinary fishing net could stop or damage an enemy drone,” Lt. Col. Maksym Kravchuk, the head of communications for the Ukrainian Army’s engineering forces, recently told Ukrainian news media. He added that nets were now being installed “along the entire front line, from east to south.”