Sightings at military bases, airports, a nuclear power station: a spate of unexplained drone flights has frayed nerves in Belgium and fueled fears the country could be being targeted by Russia.
Reports of drone activity at sensitive locations began to come out last month when suspected drones were spotted near a number of military bases in the country, said AFP.
Those sightings came as Europe was already on heightened alert after Russian drones were shot down over Poland and mysterious flights disrupted airports in Denmark and Germany.
Then last week the incidents appeared to gather pace, causing air traffic to be halted at Belgium's largest airport, the government to hold urgent talks and NATO allies to send in support.
So far, the Belgian authorities have refused -- or are unable to say -- who precisely is responsible.
Federal prosecutors have said they are probing 17 incidents.
"It is still often difficult to distinguish whether it is a local drone pilot breaking the rules or an attempt at destabilization by a state actor," the prosecutors said.
But the frequency of drone sightings have sparked strong suspicions professionals are involved -- and fingers have almost inevitably been pointed at Russia.
As tensions have surged over the Kremlin's invasion of Ukraine, Europe has accused Moscow of stepping up a "hybrid war" of sabotage, cyberattacks, and interference that float in a grey zone of deniability.
There are obvious reasons why it might be Belgium in the crosshairs right now.
At the moment, the European Union is debating unlocking a new 140-billion-euro ($162-billion) loan for Ukraine funded by frozen Russian central bank assets held in Belgium.
Even before the drone sightings, the Belgian government was warning that the move could draw Moscow's ire and put a target on the country's back.
And those worries have only been heightened by the latest activity.
"This is a measure designed to create uncertainty and fear in Belgium -- 'don't you dare touch the assets'. There's no other way to interpret it," Germany's Defense Minister Boris Pistorius said Friday.
"We can all see that, and the Belgians see it that way too."
Analysts say that drones are a low-cost and effective way to rattle a foe.
"Targeted drone overflights are almost always about unsettling the population and thereby destabilizing a country. Additionally, they are used to observe how well-prepared and equipped your opponent is," said Manuel Atug, a security expert who sits on a German working group on critical infrastructure.
"In this way, economic damage can indeed be caused, for example, through the disruption of air traffic."
Making drones even more of a problem are the difficulties facing authorities trying to identify and counter objects that can be launched at short notice from almost anywhere.
"For years, we have had drone sightings everywhere -- Germany alone has more than 100 drone sightings at its airports every year," said Ulrike Franke, an expert at the European Council on Foreign Relations.
"There is an effect where we read more about it in the press, and then the focus shifts more towards it. This plays into the hands of those who want to destabilize our countries," she said.
"Nevertheless, it is true that we currently have more sightings, especially of larger drones and over infrastructure."
Several of Belgium's NATO allies, including Germany and Britain, have sent teams and equipment to try to help, as was the case for Denmark.
Defense minister Theo Francken is now pushing for an initial 50 million euros to be spent on counter-drone defenses.
The EU for its part is working to establish a network of defenses but those will likely be more focused on its eastern border states and take years to complete.
"We cannot have 100 percent security," Franke said.
"However, there are key locations where systems should be installed: airports, nuclear power plants, liquefied natural gas terminals. This is not rocket science."
