Earlier this year, a drone carrying a tiny amount of radioactive sand was flown onto the roof of the Japanese prime minister's office. The act was a protest against the country's nuclear energy policy rather than a serious threat, but Japanese police apparently saw it as something of a wake-up call. In order to combat such aerial threats in future, Tokyo's Metropolitan Police Department has unveiled a net-wielding interceptor drone that will be used to hunt down and snare rogue quadcopters.

According to reports from The Asahi Shimbun and the Asian Review, a single drone will initially be deployed on a trial basis from mid-December. A more comprehensive operation will then be introduced in February next year, with drone squads providing protection for some of the city's most important buildings, including the Imperial Palace, the National Diet (where Japan's parliament meets), and the prime minister's office.

"Terrorist attacks using drones carrying explosives are a possibility," a member of the police department’s Security Bureau told The Asahi Shimbun. "We hope to defend the nation’s functions with the worst-case scenario in mind."

Using a net means no dropped drones

The six-rotor interceptor drone carries a 3m-by-2m net, and will only take to the air once an unlawful drone has been spotted. Police officers on the ground will use loudspeakers in an attempt to warn the drone's controller to leave the area. The use of a net to catch other quadcopters was reportedly decided on as it means less chance of an aircraft falling from the sky and injuring civilians.

Japan's police force may be one of the first law enforcement agencies to introduce countermeasures for consumer drones, but plenty of government and commercial entities are considering the same problem in the West. In November, drone maker DJI introduced new geofencing capabilities to stop its products from flying in restricted airspace, while US companies have come up with methods including net-firing guns and illegal radar jamming devices.