A man has been arrested in Fukui, western Japan, for landing a drone that was carrying a small amount of radioactive sand on the roof of the Japanese Prime Minister's home.
40-year old Yasuo Yamamoto turned himself in to police late on Friday night, claiming he landed the drone on Prime Minister Shinzo Abe's roof in protest against the Japanese government's nuclear energy policy.
Fukui is home to around a quarter of Japan's 48 nuclear reactors - all are offline after the 2011 Fukushima disaster, but Mr Abe's government wants to restart as many of the reactors as possible.
On Wednesday, a Japanese court cleared the way for the reopening of the Sendai nuclear power station in the south of the country, the first reopening of a nuclear plant since the disaster.
The small drone, which was equipped with a camera, was also carrying a plastic bottle which Yamamoto says was filled with sand from Fukushima, where radiation levels are still high after the tsunami-trigged meltdown of the Fukushima Dai-ichi power plant.
Police suspect that the bottle contained radioactive cesium - but the levels of radiation from the drone were too low to have any effect on humans or the environment.
No one was hurt in the incident, and the Prime Minister was travelling at the time of the landing.
An anti-nuclear blog which claimed to be written by the culprit said the drone was landed on the roof in the early hours of April 9.
The drone was discovered on the roof by an official, who was giving a tour of the building to new employees.
Governments around the world are struggling with how to regulate the use of drones, which are becoming increasingly sophisticated and affordable - Japan has set up a taskforce to deal control the use of drones, in an effort to protect public buildings from the security threat.
The drone incident prompted fears in Japan of remote-control devices like drones being used to commit terrorist attacks.
In January, a drone crashed on the lawn of the White House in Washington, D.C, after being flown by a scientist from the National Geospatial Intelligence Agency.
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