To catch a drone: Governments seek ways to counter tiny fliers
What's the best way to counter an unwelcome drone: a bigger, faster drone, laser guns, sky-high netting or devices that block remote controls?
Scientists, governments and companies are now scrambling to find out.
Concerned about a recent spate of mystery drones flying over its nuclear plants, military installations and even the presidential palace, France has asked scientists to help devise ways to counteract the small - and so far harmless - motorised menaces overhead.
World powers such as China and the United States are also gearing up against the potential threat.
Civilian drones have become a 21st-century hobby and a hot seller for many, from high-tech aficionados to curious kids. Companies like Amazon even want to use drones for deliveries. But their increasing presence in the skies gives headaches to national security chiefs: A small drone crashed on the White House lawn last week.
For months, France has faced dozens of drone overflights over sensitive sites - mostly nuclear facilities, a worrisome development in a country that gets the highest percentage of its energy in the world from atomic power.
French authorities say the drones currently present no threat. But some fear the drones could be spying on French technology or could one day be equipped with bombs or other weapons. Authorities have stepped up security at French nuclear sites and are investigating who might be behind the drone flights.
The possible risks of rogue drones include terrorism, the invasion of privacy, the theft of industry secrets, and "damage to the credibility of public authorities, institutions or companies", said France's National Research Agency.