Inexpensive fiber-optic drones are challenging Israel's high-tech defenses, shifting the military balance in the Middle East.

Instead of the heavy systems used by the U.S. military since World War II—missiles and ships that are expensive to design, build, and operate—this war is powered by swarms of mass-produced and oft-autonomous drones that can do the job cheaper and faster.

Wladimir van Wilgenburg stands in a residential neighborhood in Erbil, in the Kurdistan region of Iraq, and points out incoming drones high in the sky. "The U.S. defense systems, as you can see, are taking down the drones," he says in a video recorded ...

After four years of Russia's full-scale invasion, Ukraine has become far more successful at fighting off air raids.