CYIL Vol. 7, 2016

JOSEF MRÁZEK CYIL 7 ȍ2016Ȏ at the San Francisco Conference in 1945. It was replaced, therefore, with the more “neutral concept” of “armed attack”, demarcating the scope of the right of self- defence. The possibility and desirability of defining aggression was in the past for political reasons a subject of extraordinary controversy. Likewise, at the present time several question marks might be raised. Only a “significant or serious” armed attack may trigger the right of self-defence. But who will decide which armed attack is significant and serious? For many states (especially Big Powers) every attack against them will be “serious”. It would be difficult in practice to deny that any “armed attack” according to Art. 51 of the UN Charter constitutes an “act of aggression” in the sense of Art. 39 and of the 1974 Definition of Aggression. The question to reply to is which acts of aggression also represent an armed attack and if the 1974 Definition of Aggression would apply directly to the notion of “armed attack”. Res. 3314/XXIX introducing the 1974 Definition in its Preamble explicitly considers aggression as the most serious and dangerous form of the illegal use of force. This Definition, contrary to Art 2 (4), excludes “threat of force” only. The 1974 Definition enables the UNSC to exclude minor incidents, including frontier incidents, from the category of aggression when the consequences are not so serious and grave. The UNSC, as a rule, has been not willing to identify uses of force as acts of aggression. Mostly only such terms as a “breach of peace” or a “threat to peace” have been used. Not every minor “armed incident” (e.g. frontier incident) will amount to an armed attack (allowing self-defence). The concepts of “armed attack”, “act of aggression”, “crime of aggression” or generally the “notion of aggression” are closely interlinked. A number of examples of aggressive acts are shown in Art. 3 of the 1974 Definition. The element of “gravity” is mentioned in Art. 3 (g). Art. 5 stipulates: “A war of aggression is a crime against international peace.” Also the 1970 Declaration on Friendly Relations in the non-use principle provides: “A war of aggression constitutes a crime against the peace, for which there is responsibility under international law.” The legitimate question arises as to what the relationship is between “war of aggression”, “aggression”, acts of aggression”, “crime of aggression” and “crimes against or under international law”. Is one then to conceive that an “act of aggression” is a broader term in comparison to the notion of “war of aggression” or “armed attack” in modern international law terminology? It is sometimes rather difficult and artificial to differentiate notions such as “aggression”, “act of aggression” or “war of aggression”… According to the 1974 Definition of Aggression (Art 2), “the first use of armed force by a State in contravention of the Charter shall constitute prima facie evidence of an act of aggression.” The UNSC may in conformity with the Charter conclude that this determination is not justified in the light of other relevant circumstances, including the fact that the acts concerned or their consequences are not of “sufficient gravity”. It is not quite clear if “sufficient gravity” is a matter for the UNSC only to

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