Switzerland's position paper on the application of international law in cyberspace 4. Prohibition on the use of force and the right of self-defence One of the key founding principles of the UN Charter is the prohibition on the use of force (Art. 2 para. 4). There are only two exceptions: if the use of force is authorised by the UN Security Council (Art. 42) or if the strict conditions under which the right of self-defence may be exercised are fulfilled (Art. 51). The prohibition on the use of force and the right of self-defence are also applicable to cyberspace. The right of self-defence may only be exercised if an armed attack occurs first. In accordance with ICJ case law, not every violation of the prohibition on the use of force constitutes an armed attack, but only its gravest form. In order to qualify, the scale and effect of the attack must reach a certain threshold of gravity.12 The ICJ has also determined that an armed attack does not necessarily have to involve kinetic military action or the use of weapons because the means by which an attack is perpetrated is not the decisive factor. 13 A state is permitted to exercise its right of self-defence in response to a cyber incident if the incident amounts in scale and effect to that of a kinetic operation in terms of inflicting death or serious injury to persons, or extensive material damage to objects. There are no binding quant itative or qualitative guidelines as to when the threshold of an armed attack in terms of scale and effect has been reached. Current discussions on how to define an armed attack in cyberspace are focusing on attacks on critical infrastructure (e.g. nuclear power plants, power grids) which reach the required threshold in terms of scale and effect i.e. serious injury to persons and/or extensive damage to objects. The purpose of the UN Charter must guide the interpretation of the prohibition on the use of force and the right to exercise self-defence in the face of an armed attack. The Charter's objective is to maintain and, where necessary, restore international peace and security. Consequently, even if an armed attack occurs, a state is only permitted to under take countermeasures that are necessary and proportionate in order to repel the attack. The right of self-defence only applies if the UN Security Council has not taken the necessary measures to maintain international peace and security (Art. 51 UN Charter) . If the actions taken in selfdefence exceed this framework, the state itself is in breach of the prohibition on the use of force. If the threshold for an armed attack has not been reached, states can have recourse to immediate and proportionate non-violent countermeasures (see section 6.2). 5. Neutrality As a matter of principle, Switzerland considers the rights and obligations of neutral countries in international armed conflicts to be applicable to cyberspace as well.14 If such an international armed conflict arises, a neutral country has a duty to prevent any infringements of its neutrality, such as the use of its territory by one of the conflicting parties. Parties to the conflict are obliged 12 13 14 Military and Paramilitary Activities in and against Nicaragua, ICJ Reports 1986, para. 195. Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons, ICJ Reports 1996, para. 39. "The Court finds that as in the case of the principles of humanitarian law applicable in armed conflict, international law leaves no doubt that the principle of neutrality, w hatever its content, w hich is of a fundamental character similar to that of the humanitarian principles and rules, is applicable (subject to the relevant provisions of the United Nations Charter), to an international armed conflict, w hatever type of w eapons might be used." Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons, ICJ Reports 1996, para 89. 4/11