Russian forces are using explosive-packed drones connected to their operators by fiber-optic cables to deliver unjammable precision strikes on Ukrainian troops and military equipment, and Kyiv is looking for a fix to fight back.

Fiber-optic drones have been increasingly appearing in combat over about the last year, and they’re a challenge. These drones are dangerous because they can’t be jammed with traditional electronic warfare and are difficult to defend against, highlighting the need for a solution.

The drones are “a real problem” because “we cannot detect and intercept them” electronically, Yuriy, a major in an electronic-warfare unit of the Ukrainian National Guard, told Business Insider. “If we can see, we can fight.”