CYIL vol. 12 (2021)

martina Šmuclerová CYIL 12 (2021) The Tallinn Manual, a collective academic work of reference, envisages a preemptive use of force (while referring to the term “anticipatory”): “The International Group of Experts took the position that even though Article 51 does not expressly provide for defensive action in anticipation of an armed attack, a State need not wait idly as the enemy prepares to attack. Instead, a State may defend itself once an armed attack is ‘imminent’.” 18 The conditions of the exercise of preemptive self-defence are not, however, consensually defined as marked divergence of opinions prevails. In view of the disparity of visions and in order to assess the issue comprehensively, the light will be shed on the legal framework and the potential of such right. II. Self-defence in Article 51 of the UN Charter The right of a State to self-defence constitutes one of the two exceptions to the general prohibition to use force in international relations enshrined in Art. 2 (4) of the UNCharter that are expressly laid down in the UN Charter. 19 The legal regime of the recourse to self-defence is elaborated in detail in Art. 51. It stipulates explicitly in the first phrase that “[n]othing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security”. 20 Besides other interesting aspects of this provision to be discussed, the key element for the assessment of preemption is the requirement of an “armed attack to occur”. This prerequisite explicitly refers to an existing armed attack, in other words an attack that has effectively happened, which dismisses any future, or potential attack regardless of its degree of imminence, probability or other temporal aspect. The International Court of Justice emphasized the requirement of the presence of an armed attack for the exercice of self-defence in its judgement of 27 June 1986 in the case concerning Military and paramilitary activities in and against Nicaragua (hereafter “ Nicaragua Case”): “In the case of individual self-defence, the exercise of this right is subject to the State concerned having been the victim of an armed attack. Reliance on collective self-defence of course does not remove the need for this. There appears now to be general agreement on the nature of the acts which can be treated as constituting armed attacks. In particular, it may be considered to be agreed that an armed attack must be understood as including not merely action by regular armed forces across an international border, but also ‘the sending by or on behalf of a State of armed bands, groups, irregulars or mercenaries, which carry out acts of armed force against another State of such gravity as to amount to’ (inter alia) an actual armed attack conducted by regular forces, ‘or its substantial involvement therein’.” 21 experts on developments in the field of information and telecommunications in the context of international security, Note by the Secretary-General , UN Doc. A/68/98, 24 June 2013, pp. 2, 4, and 8, available at . 18 Schmitt, M.N. (ed.), Tallinn manual 2.0 on the international law applicable to cyber operations . Cambridge, 2017, p. 350 (hereafter as “Tallinn Manual” ). 19 The other lawful recourse to use of force is a military operation authorized by the UN Security Council as elaborated in Chapter VII, Art. 42, of the UN Charter. 20 Emphasis added. 21 Military and paramilitary activities in and against Nicaragua (Nicaragua v. United States of America ), judgement of 27 June 1986, ICJ Reports 1986 , § 195.

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