450 DENMARK held that States are prohibited from intervening directly or indirectly in internal or external affairs of other States.1 In order for an action to qualify as an unlawful intervention it must qualify as an intervention in matters that are the sovereign prerogative of a State, the so-called domaine réservé, and it must involve an element of coercion.2 The scope of activities falling within the domaine réservé include but are not limited to “ (…) the choice of a political, economic, social, and cultural system, and the formulation of foreign policy.”3 The range of activities covered by the non-intervention rule largely overlap with the activities reserved to States under the rule of sovereignty. The term coercion is not defined in either treaty law or customary international law. Denmark takes the view that an act may be considered of a coercive nature when the act of interference has a potential for compelling the target State to engage in an action that it would otherwise not take. However, a distinction must be drawn between activities that merely involve influencing, as opposed to compelling, the voluntary actions of a target State. Acts of influence, such as persuasion, criticism, and public diplomacy are insufficient to qualify as an intervention. To be coercive the effort to intervene must be designed to have a decisive impact on outcomes or conduct with respect to a matter reserved to the target State. As emphasized by the Court in the Nicaragua judgment coercive acts involving the use of force are particularly obvious examples of unlawful interventions.4 Denmark considers that coercion is not limited to means of direct or indirect use of force and that also measures below this threshold may constitute coercion. Cyber activities that do not amount to use of force can therefore also be coercive. An example of unlawful intervention in the cyber domain could be where a State coercively interferes in the internal political process of another. In the cyber context this could potentially occur by using cyber technology to alter electronic ballots and thereby affecting the results of a political election. 4 Use of force and self-defence Cyber operations may violate the prohibition on the threat or use of force, which primarily depends on the physical scale and effects of the cyber operation in question. It requires an individual assessment of the specific circumstances 1 Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America case). Merits, Judgment. ICJ Reports 1986, p. 14, para. 205. 2 Ibid. 3 Ibid. 4 Ibid. Downloaded from Brill.com 03/27/2024 10:42:51AM via Open Access. This is an open access article distributed under the terms Nordic Journal of International Law 92 (2023) 446–455 of the CC BY 4.0 license. https://creativecommons.org/licenses/by/4.0/