Unidentified drones, which flew over Paris for a second night in a row on Wednesday, are only the latest mystery appearances of the unmanned aircraft over France's skies at a time of high security.
The sightings follow a series of drone spottings at French atomic plants late last year and, more recently over the presidential palace and a bay in Brittany that houses nuclear submarines.
Other European countries have seen drone movements, albeit on a lesser scale:
On December 20, 2014, an unexplained drone is spotted flying over Belgium's Doel nuclear facility near Antwerp, a day after one of the plant's reactors comes back on line after a four-month closure caused by sabotage.
On July 22, 2014: an Airbus A320 passenger jet is involved in a near-miss with a drone at London Heathrow, one of the world's busiest airports, an official report issued in December says. In January the press reports that drones also flew over London's Shard, Tower Bridge and the London Eye.
On September 16, 2013, a small drone hovers over a campaign rally in Dresden by German Chancellor Angela Merkel before crash landing in front of her in a protest by the upstart Pirate party.
In October, 2014 a Euro 2016 soccer qualifier between Serbia and Albania is abandoned after fighting breaks out among players and fans on the pitch over a "Greater Albania" flag that is flown above the stadium by a drone.
An overflying drone in late 2014 forces Stockholm's Bromma airport to halt air traffic. It later emerges that the drone was being used by an individual to collect data on a construction site.
On September 7, 2014, a one-metre-diametre drone crashes in Geneva on an avenue, closely missing a car.
Meanwhile, in the UNITED STATES, a small drone crash-landed on the grounds of the White House on January 26, 2015, prompting officials to declare a security lockdown until they were able to determine that it posed no risk.
President Barack Obama and his wife Michelle were at the time on an official visit to India.
The drone was operated by a government employee who told the Secret Service he did not mean to fly the device over the White House grounds.