The meaning of aggression

327. The terms ‘aggression’ and ‘aggressor’ are constantly used in the context of the unlawful use of force by States. This is done even in key provisions of binding treaties – preeminently, the Charter of the United Nations (see especially Article 39 quoted infra 810) and the Vienna Convention on the Law of Treaties (see Article 75 quoted supra 109) – which do not make any attempt to define aggression. Needless to say, absent a definition, the precise contours of aggression lend themselves to heated discussions and disagreements.

328. Efforts to arrive at a definition of aggression in a binding form were made in a series of agreements concluded by the USSR with neighbouring countries already in 1933. But these definitions leave a lot to be desired and obviously they were never applicable to non-Contracting Parties. Within the framework of the United Nations, endeavours to define aggression started early on. It took quite some time before the impetus favouring such a definition overcame resistance that, initially, was considerable. However, in 1974 the General Assembly managed to adopt by consensus its landmark Definition of Aggression (cited supra 192). The text has proved to be widely – albeit not universally – accepted in the legal doctrine. Moreover, at least one Paragraph of the Definition (namely, Article 3(g), to be quoted infra 367) was taken by the International Court of Justice – in the Nicaragua case of 1986 – ‘to reflect customary international law’; and the Court relied on that provision again in the 2005 Armed Activities case. As we shall see (infra ibid.), in 2010 the whole of Article 3 was incorporated into a new Article 8 bis of the Statute of the International Criminal Court. Indisputably, the General Assembly Definition of Aggression may now be viewed as the most authoritative text on the subject.