The Challenges Posed by Cyber Attacks to the Law on Self-Defence

States have become increasingly dependent on computers and the networks that connect them. The development of cyber space enables States and non-State actors to increase their offensive capabilities significantly. Cyber attacks can now be carried out more easily and with a lower risk of detection than attacks with conventional weapons. These attacks may produce effects that are not only internal to a computer or network but also external, by causing harm to connected facilities which could in turn lead to serious physical harm to property or individuals. Such would be the case for example when a computer network attack disables an air traffic control system and causes an airliner to crash. This paper addresses a number of challenges posed by cyber attacks to the law of self-defence. Section II outlines the international criteria for the attribution of a cyber operation to a State. Section III argues that only cyber attacks reaching the level of an armed attack give the right to the victim State to use self-defence. Section IV explains that the law on self-defence does not offer an effective response to cyber attacks because, as international law stands, only cyber attacks attributed to States trigger the right to self-defence. Section V concludes that current international law on self-defence needs to be adapted to meet the challenges posed by cyber attacks.