A/76/136 Moreover, according to AP I, States have an obligation, “in the study, development, acquisition or adoption of a new weapon, means or method of warfare,” to “determine whether its employment would, in some or all circumstances,” be prohibited. 40 This norm, although being less strict than some States wished during the negotiations of AP I, 41 already encompasses some precautionary elements. It must guide the development, acquisition and adoption of cyber capabilities. In making the assessment of necessity, distinction, proportionality and precaution, parties must take into consideration the particularities of the cyberspace, such as the interconnectivity between military and civilian networks. The principle of distinction determines that cyberattacks must target military objectives and must not be indiscriminate. In case of doubt whether a cyber infrastructure that is normally dedicated to civilian purposes is being used to make an effective contribution to military action, it shall be presumed not to be so used. 42 While holding the view that IHL applies to cyberspace, there are issues that deserve further reflection, such as the definition of cyberattack for the purposes of article 49 of AP I; the consideration of civilian data as a civilian object that entails protection under IHL; and when a civilian acting in the cyberspace might be considered as taking direct part in hostilities. In any event, where IHL is silent or ambiguous, the “Martens clause” remains applicable, 43 ensuring that, in cases not covered by existing rules, “civilians and combatants remain under the protection and authority of the principles of international law derived from established custom, from the principles of humanity and from the dictates of public conscience”. 44 Estonia [Original: English] Estonia welcomes the opportunity to submit its national contribution on the subject of how international law applies to the use of information and communications technologies (ICTs) by states as an annex to the report of the UN Group of Governmental Experts, as requested by UN General Assembly Resolution 73/266. Estonia reiterates that existing international law applies in cyberspace. The rights and obligations set out in international law, including the UN Charter in its entirety, customary international law, international humanitarian and human rights law, apply to the use of ICTs by states. This means that international law applies to relations between states in cyberspace as it does in conventional domains of state interaction. To promote peace and stability in cyberspace and prevent conflict, it is necessary to have clear rules of responsible state behaviour in place. Existing international law provides a solid normative framework for state actions, regardless of the means or the environment for these actions. The applicability of international law in cyberspace has been affirmed by the UN General Assembly endorsements of the 2013 and 2015 UN Group of Governmental Experts __________________ 40 41 42 43 44 21-09670 Additional Protocol I, art. 36. ICRC Commentary of 1987, API, art. 36. Additional Protocol I, art. 52. ICJ, Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons, p. 260. Additional Protocol I, art. 1. 23/142