Introduction
A fundamental objective of the modern international legal order, which is founded upon the Charter of the United Nations, is the maintenance of international peace and security. The Charter contains at least 35 references to “peace” as a sought state of international relations and a value protected by international law,1 and its derivations (e.g., “peaceful”, “pacific”, “peace-loving”) are mentioned in at least nine further Articles of the Charter.2 To reinforce international peace and security, Article 2(4) of the Charter laid down a stringent restriction on the use of force in international relations, an obligation which was, from its inception, designed to be of a superior legal nature3 and is now recognised to have acquired the character of customary international law and even that of jus cogens. Notably, Professor Peter Malanczuk suggests that this norm is now binding even for the few States which are not members of the United Nations.4
Permitted uses of force are regulated by a sequence of the Charter’s provisions, which is opened with the seventh preambular paragraph: “[T]o ensure, by the acceptance of principles and the institution of methods, that armed force shall not be used, save in the common interest” (emphasis added). Although the Preamble does not per se have a legally binding effect, it does give an indication as to the spirit of the subsequent operative articles. In line with the Preamble’s “common interest” clause, Article 1(1) lists “effective collective measures for the prevention and removal of threats to peace, and for the suppression of acts of aggression or other breaches of peace” among the purposes of the United Nations.5 At least two of the United Nations main organs, the General Assembly (Article 12) and the Security Council (Articles 24(1) and 39), were given explicit powers to react, albeit in dissimilar ways, to threats to peace, breaches of peace and acts of aggression. The entirety of Chapter VII (“Action with Respect to Threats to the Peace, Breaches of the Peace, and Acts of Aggression”) and VIII (“Regional Arrangements”) are devoted to the maintenance of international peace and security through collective action under the aegis of the United Nations or regional arrangements. More specifically, Article 42 endows the Security Council with the authority to “take such action by air, sea or land forces as may be necessary to maintain or restore international peace and security”.6 Article 43 sets a framework for the conclusion of agreements and arrangements between the United Nations Member States contributing to the maintenance of international peace and security and the Security Council.7 Article 44 regulates the specific relations between the Security Council and Member States who, not being members of the Security Council, participate in such operations.8 Article 51 recognises the Member States’ “inherent right to self-defence” against armed attacks.9 Article 53(1) provides that armed force in the form of an “enforcement action” may also be used by the Security Council through regional arrangements.10 Finally, Articles 53 and 107 address the use of armed force, where necessary, against former enemies in the Second World War.11
During the period since the 1999 NATO operation in Kosovo, and especially in connection with the US-led Operation Enduring Freedom (Afghanistan) and, subsequently, Operation Iraqi Freedom (Iraq), a number of novel doctrines have been put forward with a view to justifying these uses of force – potentially an important development in a field of international law as conservative as the post-1945 jus ad bellum,12 for, at times, these doctrines claimed to be as far-reaching as to be able to modify the Charter’s provisions on the use of force. In contrast, it will be argued in this essay that Article 2(4) and other relevant international law should not be interpreted in too broad a manner,13 and that any use of force in inter-State relations which is not plausibly compatible with the overarching prohibition contained in Article 2(4) would accordingly constitute a breach of the Charter.14
December 14, 2009 will mark the 35th anniversary of the United Nations’ Definition of Aggression – an international instrument that sought to reinforce the safeguarding of international peace and security by way of interpreting Article 2(4) of the Charter of the United Nations and defining – albeit in a non-binding way – a key concept in contemporary public international law. In honour of this important anniversary, this essay will recall some landmark features of that Definition and then proceed to analysing the Definition’s “parent provision” – Article 2(4) of the Charter – with a view to reaffirming its status as a superior norm of international treaty law and a rule of customary international law. The essay will conclude with the characterisation of Article 2(4) as a peremptory norm of general international law (jus cogens) from which no derogation is allowed.
Elements of an Act of Aggression Under The 1974 Definition of Aggression
General Assembly Resolution 3314 (XXIX) was adopted on 14 December 1974, as an interpretation of Article 2(4) of the United Nations Charter, with a Definition of Aggression annexed to it.15 Constructed, to a substantial extent, upon the draft definition of aggression proposed by the Soviet Union in 1933, and upon alternative drafts offered by the Soviet Union and groups of Western and developing States during the 1950s and 1960s,16 the new Definition was adopted, almost 30 years after the entry into force of the Charter of the United Nations, as a guideline for the Security Council’s determination of the existence of an act of aggression17 and was commonly (although not universally) recognised.18 A useful interpretative tool, the Definition – as a General Assembly resolution – was nevertheless not legally binding, and the Security Council “never relied on the 1974 Resolution to determine that the given situation constitutes aggression”.19 Although the 1974 Definition lacked a binding legal force and suffered from a number of structural and substantial deficiencies, it is still worth considering here in some detail, as its content has exercised a considerable impact on the drafting of a number of further international instruments, including the definition of the crime of aggression for the purpose of the International Criminal Court.20
“Chapeau” of the definition
The 1974 Definition contains a general part followed by an incomplete list of examples of acts of aggression. The general part of the Definition (Article 1) reads as follows:
Aggression is the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations, as set out in this Definition.
Professor Yoram Dinstein singled out six essential distinctions between this relatively advanced formulation and the primary rule articulated in Article 2(4) of the Charter of the United Nations: (1) the mere threat of force is excluded; (2) the adjective “armed” is interposed before the noun “force”; (3) “sovereignty” is mentioned together with the territorial integrity and the political independence of the victim State; (4) the victim is described as “another” (rather than “any”) State; (5) the use of force is proscribed whenever it is inconsistent with the United Nations Charter as a whole, and not only with the Purposes of the United Nations; (6) a linkage is created with the rest of the Definition.21 It has been suggested that the adding of a number of extra elements to the definition of aggression was just intended to raise the assessment threshold and accordingly to do away with the possibility of invoking shooting “a few stray bullets across a boundary” as the commission of an act of aggression by a State.22 However, the impact of this important – indeed, progressive – development in international law could have been more far-reaching. Its more precise wording, in comparison with Article 2(4) of the Charter, could have made the Definition a workable tool for protecting sovereign interests of individual States and for maintaining international peace and security alike, and so would have reinforced the impact of Article 2(4) itself. The problem with the Definition was its recommendatory status of an annex to a General Assembly resolution.23 If the Definition had been bestowed with an adequate legal force – for instance, by way of approval by the Security Council whose decisions are mandatory for all Members of the United Nations24 and the carrying out of whose foremost function25 the Definition was intended to facilitate – it would have become a “harder” source of international law and should have been complied with by States in a more consistent manner.
Examples of acts of aggression
In furtherance of the general part, Article 3 of the Definition lists possible examples of acts of aggression, regardless of their being accompanied by a declaration of war:
- The invasion or attack by the armed forces of a State of the territory of another State, or any military occupation, however temporary, resulting from such invasion or attack, or any annexation by the use of force of the territory of another State or part thereof;
- Bombardment by the armed forces of a State against the territory of another State or the use of any weapons by a State against the territory of another State;
- The blockade of the ports or coasts of a State by the armed forces of another State;
- An attack by the armed forces of a State on the land, sea or air forces, or marine and air fleets of another State;
- The use of armed forces of one State which are within the territory of another State with the agreement of the receiving State, in contravention of the conditions provided for in the agreement or any extension of their presence in such territory beyond the termination of the agreement;
- The action of a State in allowing its territory, which it has placed at the disposal of another State, to be used by that other State for perpetrating an act of aggression against a third State;
- The sending by or on behalf of a State of armed hands, groups, irregulars or mercenaries, which carry out acts of armed force against another State of such gravity as to amount ...