A man flew a drone, carrying radioactive sand, and landed it on to the roof of Japanese Prime Minister Shinzo Abe's office, Tokyo police reported.
40-year-old Yasuo Yamamoto is a nuclear protester and targeted the prime minister over his government's nuclear energy policy.
The drone carried traces of radiation; however the amount was too small to harm anybody.
The incident caused a security alert and raised fears that extremists might use drones to carry out their attacks, following Yamamoto's example.
