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Two civil jamming devices. Photo: FOI.

Electronics make society vulnerable to antagonistic attacks


Knocking out mobile networks, traffic signals, or radio and TV broadcasts are an increasingly common feature of international conflicts. For decades, military electronic warfare has been an effective means of gaining an advantage on the battlefield. But this and other antagonistic electromagnetic threats have become a reality that even civil society must deal with.

At the request of MSB, the Swedish Civil Contingencies Agency, FOI has conducted several projects concerning electromagnetic threats (EM threats). These include both communications jammers that can use radio noise to drown out the information on a communications channel, as well as microwave weapons that are currently being developed by a number of armed forces. EM threats occasionally resemble cyberthreats but use electromagnetic radiation to strike hardware directly. The more powerful kinds can knock out many different types of electronics, even those that neither communicate nor handle data.


Civil defence is unprepared

The aim of the current assignment is to increase knowledge of society’s vulnerability to intentional EM attacks – so-called antagonistic EM threats – by foreign powers, terrorists, or criminals. This is part of the reconstruction of civil defence.


“The last time we had a strong civil defence, electromagnetic threats were not as important as they are today. In parallel with the introduction of electronics for use in ever more societal functions, it has become easier to obtain jamming devices. In addition, someone who wants to build one of the simpler microwave weapons can find lots of information about it on the Internet,” says Sten E Nyholm, Deputy Research Director at FOI, and responsible for a couple of the projects that FOI has carried out at the request of MSB.


Society’s growing dependence on electronic communications, control, surveillance, and security systems has increased our vulnerability. Industrial command and control systems manage electricity production, water supply, sewage, and traffic signals that regulate highway and rail traffic. Society’s communications systems, such as radio, TV, and the Internet are also dependent on electronic equipment.


Protection from EM threats

The following five strategies are important for protection from EM threats:

  • Information restrictions: Restrict open access to information that can be used for an EM attack.
  • Wired communication for critical connections: Do not use wireless communication in critical operational systems!
  • Protect with distance: The further the barricade or fence is from the system needing protection, the less is the effect of the EM threat.
  • Perimeter protection: Install protective shielding around sensitive equipment.
  • Transient protection and filter: Install transient protection and filters on cables and cable entrances.