In April 2015, Yasuo Yamamoto flew a drone carrying radioactive sand on to the roof of the Japanese prime minister’s office. A man was protesting over Japanese government’s nuclear energy policy. Police said that the material was likely to be caesium but the levels were too low to harm a human health. No-one was hurt and Prime Minister Shinzo Abe was out of the country while that incident occurred. Yamamoto was given two-year suspended sentence.

Although, it had caused a and embarrassment to the authorities for the security breach and for the delayed discovery of the drone. That incident has led to wide-reaching changed to regulations on those aircrafts in Japan.