Drones: The threat from above

Published: 09.02.23

They are difficult to detect and virtually impossible to defend against. Drones have moved into the air space and are forcing a paradigm shift in the way we need to approach security.

Last summer, a German man was just under four kilometres from the Danish air base at Karup. He sent his drone up to a height of 96 metres, which was more than twice what he was allowed to do – even if he did have a drone certificate. He should also have been at least eight kilometres away from the military airport. The outcome was that air traffic to and from the airport was paralysed – and the German was fined DKK 2,500 and had his drone confiscated by the police.

“This incident is a good example of the major security challenges that drones present. This was a drone operator who had no evil intentions. Just imagine what a drone operator who wants to do harm could do,” says Troels Boe, referring to the fact that unknown drones created concern earlier this year by hovering over several Swedish nuclear power plants.

In his daytime job, he is an official at the Danish Transport Authority, but it is through his Master’s degree in International Security and International Law, for which he wrote a thesis on drone security, that he deals with the challenges that civil drones present in connection with what he refers to as “the democratisation of airspace”. This has seen a shift from all airborne mechanics being classified as aviation, with the associated regulation, to anyone and everyone – like the German – being able to buy a drone and create havoc. Be it unintentional or intentional.

“Drones represent a paradigm shift. They fundamentally change the way we must approach security. Ever since the first ring fortresses, we’ve believed that if we just built defences that were sufficiently wide and tall, we were safe. But you can’t divide the air space with physical obstacles in the same way,” says Troels Boe.

Drone attack on Parliament building

He argues that the arrival of drones means that we must consider security in 3D instead of 2D – in volume instead of on the level.

“The Swedes were able walk over the ice and attack the Danes in the 17th century because the barrier between areas of land – water – froze solid and joined them together on one level. Correspondingly, if you open a window, for example, you remove the barrier between two volumes: the volume you are in and the biggest volume there is, the sky outside. And drones move through volumes,” says Troels Boe, citing the parliament building as an example:

“Large granite balls have been erected to protect against terrorism, but once more, this only protects on one level. When it’s hot in the summer, windows in the building are wide open, so a drone could potentially fly in and cause damage,” he says.

You could almost say that only the imagination limits what a drone and a competent drone operator could potentially do at the parliament building or in any other building that is not hermetically sealed. A drone can carry a bomb, it can photograph documents that are left out in full view, or it can land in a discreet place and set up a fake wireless network to intercept logins, etc. or transmit confidential conversations via a microphone.

Prisons are powerless

Transporting objects in particular is now a familiar problem for prisons, where drones are used to fly items such as mobile phones over the fence to inmates.

“It’s almost impossible to stop them,” says CTO Toke Kristian Suhr from Droner.dk, which sells drones and offers training on their use.

As a professional, he knows what civil drones are now capable of, which is why he has been advising Danish prisons on protection against drones. But even high-security prisons with high fences and strong walls cannot stop drones that weigh just a couple of kilogrammes.

“Some prisons have a frequency scanner that triggers an alarm if a drone overflies the prison area. But even though it can point the prison staff towards where the drone and potentially the drone operator are, the information is used reactively to shut down and search through the prison block where the object from the drone may have come in. Using a drone for transport like this is simply so fast that staff don’t have time to respond while it’s happening,” says Toke Kristian Suhr.

Traffic legislation for drones

From abroad, he has seen many creative solutions aimed at rendering drones harmless – including nets that are launched into the air and training eagles to attack drones. But according to Toke Kristian Suhr, it is only frequency jamming, which interrupts the drone operator’s control of the drone, that works in practice.

“But jamming is not permitted by the Danish authorities, and there’s no guarantee that the drone won’t find its way anyway – even if the GPS signal is disrupted. Developments are moving at a rapid pace, and the defence industry has developed drones that can find their own way by recognising their surroundings,” says Toke Kristian Suhr.

Troels Boe summarises the security issue that drones pose:

“They are difficult to detect and virtually impossible to defend against. A handful of civil and military airports have radar and permanent staff to discover drones, but the rest of Denmark is a blank map. If a citizen calls the police because, for example, a drone is flying illegally over an area of summer cottages, it’s unlikely that the police will be able to locate or pursue it before the drone has gone again,” says Troels Boe. He recommends in the first instance a review of how to better train those drone operators who do not have any malicious intentions and who are responsible for the majority of the incidents involving drones in Denmark.

“But the categorisation as aviation is still alien for many users, who may unsuspectingly find themselves in violation of the principles of aviation. Another solution is to take a more holistic view of the opportunities and challenges that come with drone technology. A good place to start would be a thorough update of the national drone strategy from 2016, which has long since been overtaken by reality,” suggests Troels Boe.