unnecessary suffering and superfluous injury, apply to cyber attacks in international as well as in non-international armed conflicts. Germany defines a cyber attack in the context of IHL as an act or action initiated in or through cyberspace to cause harmful effects on communication, information or other electronic systems, on the information that is stored, processed or transmitted on these systems or on physical objects or persons.34 The occurrence of physical damage, injury or death to persons or damage or destruction to objects comparable to effects of conventional weapons is not required for an attack in the sense of art. 49 para. 1 Additional Protocol I to the Geneva Conventions.35 However, the mere intrusion into foreign networks and the copying of data does not constitute an attack under IHL. (1) The prohibition of indiscriminate attacks and cyber operations The principle of distinction obliges States to differentiate between military and civilian objects, as well as between civilians, on the one hand, and combatants, members of organized armed groups and civilians taking direct part in hostilities, on the other hand. While IHL does not prohibit an attack on the latter, civilians (not taking direct part in hostilities) and civilian objects must be spared. Civilians operating in cyberspace can be considered as taking direct part in hostilities with the result of losing their protection from attack and the effects of the hostilities, provided the following conditions are met: Their acts are likely to adversely affect the military operations or military capacity of a party, there is a direct causal link between their acts and the adverse effects and the acts are specifically designed to inflict harm in support of a party to an armed conflict and to the detriment of another (belligerent nexus).36 Thus, Germany agrees with the view that, for example, ‘electronic interference with military computer networks […], whether through computer network attacks or computer network exploitation, as well as wiretapping […] [of an] adversary’s high command or transmitting tactical targeting information for an attack’, could suffice in order to consider a civilian person as directly participating in hostilities.37 Following the same logic, a civilian object like a computer, computer networks, and cyber infrastructure, or even data stocks, can become a military target, if used either for both civilian and military purposes or exclusively for the latter. However, in cases of doubt, the determination that a civilian computer is in fact used to make an effective contribution to military action may only be made after a careful assessment.38 Should substantive doubts 34 35 36 37 38 See also NATO Terminology Tracking Form (TTF) 2015-0028 (last entry 2019-02-12). Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I), 8 June 1977, 1125 UNTS 3. International Committee of the Red Cross (ICRC)/Melzer, N., Interpretive guidance on the notion of direct participation in hostilities under international humanitarian law, 2009, available at www.icrc.org, p. 16. Ibid., p. 48 (footnotes omitted). Tallinn Manual 2.0 (note 4), rule 102. 8