Drones have harassed airports and bedeviled local police. They have trespassed over nuclear plants and prisons. On the battlefield, they can kill.

But aside from shooting down the devices, which may create further danger, there is often not much anyone can do to stop drones when they pose a threat or wander where they are not welcome.

That is beginning to change. Cheap and easily modified, unmanned aerial vehicles have become a part of daily life as well as a tool for governments and bad actors alike — used for intelligence gathering, surveillance, sabotage, terrorism and more. Concerns about their misuse have spurred a technological scramble for ways to stop the devices in midair.

“An adversary can use an off-the-shelf drone they bought for $500 and find out what’s going on at U.S. nuc

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