GENEVA — Drones are increasingly hovering over our heads. In the past six months, dozens of them were seen flying in France over sensitive Parisian sites, military installations and nuclear power plants. And with the threat of terrorist attacks, these machines are a real source of concern for the military and the police, and not just in France.

"Drones sold in shops for between a few hundred and a few thousand Swiss francs are made to transport cameras that weigh between 800 grams and 4 kilos," says Alexandre Vautravers, editor in chief of the Revue Militaire Suisse. "It's easy to attach a 500-gram hand grenade and to add a mechanism allowing it to be triggered remotely with a cellphone. It's not much different from the system that triggers camera shutters, and it can be cobbled together without in-depth know-how. It is commonly used in Afghanistan and in Iraq by rebels who've never set foot in an engineering school."

This assessment is all the more alarming because a hand grenade is a powerful weapon. Thrown into a crowd, it can kill dozens of people. In a confined space, its destructive power is much bigger.

Charlie Hebdo caricature of French President Hollande, asking "Who's afraid of drones?" — Source: dronyair via Instagram

"Non-weaponized drones, equipped just with a camera, can also be used for terrorist attacks," Vautravers explains. "They can collect specific information about sensitive sites. Aerial pictures can show wall thickness and thus indicate building strength."

These devices also make attacks with bazookas or mortars easier. They can communicate in real time the exact location of targets to shooters hundreds of meters, or even several kilometers, away. And after a failed first salvo, they can even "put things right."

A very real threat

This isn't science fiction. An attack with a miniature drone could happen at anytime. And in security circles, nobody doubts that this possibility is being seriously considered by criminal organizations. It's become urgent to establish a series of defensive measures.

The first type is "kinetic," meaning a defense mechanism that relies on hitting the flying device with another moving body. In more practical terms, this consists of detecting the drone with a radar or an optical device and then hitting it with a projectile. "A sharpshooter is one good way to do it," Vautravers says. "There's a very good chance he'll hit his target from a distance of 1,000 meters. It doesn't cost a lot, and it represents no danger for third parties. We can also use automated systems connected to cannons or missiles, but their heavier ammunition risk causing significant collateral damage."

[rebelmouse-image 27088744 alt="""" original_size="1024x1024" expand=1]

Photo: Doctor Popular

Another type of defense is "electromagnetic," consisting of scrambling the signals between the drone and its pilot to render the device uncontrollable and to therefore scuttle a planned attack. But this necessitates that the areas and frequencies used are properly defined so as to limit unwanted damage.

Finally, the third type of defense is the law. "A certain number of countries, including the United States, are already working on it," Vautravers explains. "Lawmakers can, for example, force makers to install GPS chips on their drones so as to limit their access to certain areas."

It's still uncertain how big a danger these small flying devices represent for our societies. "In any such analysis, two factors need to be taken into account: the seriousness and the probability of the feared event," Vautravers notes. "About the first point, if an attack carried out with a miniature drone had a massive media impact, it wouldn't necessarily victimize a large number of people. About the second point, however, there's no doubt about it: We're already there."

So what should we do? Because it would be way too expensive to protect everything at all times, it seems wiser to defend in priority the most symbolic targets, like nuclear power plants, military installations and large rallies. And not just because of their own importance. Preventing attacks with an important media impact also means making attacks less attractive for terrorists, and thus, in principle, drastically limit their number.