The discovery on April 22 of a drone on the roof of the prime minister's official residence points to a lapse in security measures. Attached to it was a small container filled with radioactive earth and soil. If the radiation had been stronger, it could have posed a danger to people. The suspect who was subsequently arrested said the radioactive material was from Fukushima.

This incident took place at a time when the use of drones is rapidly growing. Apart from the need to beef up security measures at government buildings, the incident has underlined the need for the government, the public and lawmakers to discuss how to adequately regulate the use of drones while ensuring that their usefulness is not impaired.

Until recently, drones in Japan were mainly used for applications such as spreading agricultural chemicals, and currently about 2,500 drones for agricultural use are in operation. But in recent years the use of drones has been expanding and now they are being used to take photographs of places that people cannot easily access, such as natural disasters, and structures like bridges, gas and oil tanks and wind turbines.