A/76/136 Amongst the gravest forms of the use of force in international relations are armed attacks, 22 which trigger the right of states to resort to self-defense, in accordance with article 51 of the UN Charter. Being self-defense an exception to the general principle on the prohibition to the use of force, it needs to be interpreted restrictively. This view is in line with the case law of the International Court of Justice, the principal judicial organ of the United Nations. 23 As a consequence, self-defense is only triggered by an armed attack undertaken by or attributable to a State. 24 It is not possible to invoke self-defense as a response to acts by non-State actors, unless they are acting on behalf or under the effective control of a state. This norm becomes even more relevant with cyber operations, where technical, legal and operational challenges to determine attribution might make it impossible to verify potential abuses of the right of self-defense, which in turns creates the risk of low impact persistent unilateral military action undermining the collective system established under the Charter. In the same vein, contemporary international law does not allow for self-defense on the basis that the territorial state would be “unwilling and unable” to repress nonstate actors whose cyber acts have extraterritorial effects. The definition of “armed attack” is limited to the use of force attributable to a state and, therefore, actions from non-state actors with similar effects might amount to serious crimes, but not an “armed attack”. If such a situation arises, the territorial state should adopt measures, in good faith and within its capabilities, to cease the action and ensure accountability. If it fails to do so, this omission might constitute an internationally wrongful act, thus entailing this states’ international responsibility. According to customary international law, in this case the victim state is entitled to remedies, to be pursued only through peaceful means. Moreover, self-defense should be a temporary remedy. Member states that exercise their right to self-defense must immediately report it to the Security Council, in line with article 51 of the Charter. Given the novelty of cyberattacks and the uncertainties related to it, reporting to the Security Council is even more important. As the ICJ highlighted, “the absence of a report may be one of the factors indicating whether the State in question was itself convinced that it was acting in self-defense”. 25 Once the incident is reported to the Security Council, it is expected that the temporary act of self-help is replaced by collective action, adopted and pursued in line with the UN Charter. For Brazil, the right to self-defense exists once there is an actual or imminent armed attack. Under international law, there is no right to “preventive self-defense” a notion that does not find legal grounds neither in art. 51 of the Charter nor in customary international law. Finally, as with responses to armed activities using conventional weapons, self-defense against armed attacks caused by digital means must be necessary and proportionate. 26 4. State Responsibility Brazil agrees with the basic principle according to which “every internationally wrongful act of a State entails the international responsibility of that State”. 27 This is __________________ 22 23 24 25 26 27 20/142 ICJ, Nicaragua, p. 91; ICJ, Oil Platforms (2003), para 64. See, e.g., ICJ, Armed Activities on the Territory of the Congo (Democratic Republic of the Congo v. Uganda), p. 123 (“Article 51 of the Charter may justify a use of force in self-defence only within the strict confines there laid down”). ICJ, Armed Activities, p. 223. ICJ, Nicaragua, p. 105 ICJ, Oil Platform, p. 196–197 ILC, Articles on State Responsibility for Internationally Wrongful Acts, article 1. 21-09670