CYIL 2014

THE DEFINITION OF AGGRESSION AND THE USE OF FORCE

of aggression constitutes a crime against peace for which there is responsibility under

international law”. The reference to “crime against international peace” is also contained

in Art. 5 (2) of the 1974 Definition. Both these stipulations were consistent with the

former Art. 19 of the Articles on State Responsibility.

In the final version of the

Articles on State Responsibility the reference to “crimes” of states was deleted. The

ILC finally came to the conclusion that a “crime of aggression” is a penal matter not

relevant to state responsibility.

The IMT in Nuremberg declared “aggression” as the “supreme international crime”,

without any special definition of the crime of aggression. It is clear that not all

illegal use of force amounts to aggression. According to Mary E. O’Connell

only

a “significant or serious” armed attack may trigger the right of self-defense”. In her

view not all acts of aggression amount to a “significant and serious armed attack”

or represent at the same time “a war of aggression”. With regard to the Kampala

definition it is obvious that all acts of aggression do constitute “crimes of aggression”

or “war of aggression”.

A. Cassese maintained that the 1974 Definition was left deliberately incomplete,

not exhaustive and leaving to the UNSC a broad area of discretion.

In the Nicaragua

case the ICJ held that an armed attack must be understood as including ,,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 amount (

inter

alia

) to… an actual armed attack conducted by regular forces.” This stipulation,

contained in Art. 3 (g) of the Definition, may be, according to the ICJ, taken to

reflect “customary international law” and may be classified as ,,an armed attack”

rather than as a mere frontier incident. The ICJ expressed its belief that the concept

of “armed attack” includes assistance to rebels in the form of the provision of weapons

or logistical or other support.

Judge Schwebel and Judge Jennings criticised in their

dissenting opinions the ICJ definition of “armed attack as excessively narrow.”

The

stipulation on “substantial involvement” is rather unclear as to whether it also covers

the case when a state supplying weapons to armed bands which launch attacks from

the territory of another state against a third state. The term “substantial involvement”

relates clearly to the case when a state permits an armed band to use its territory for

launching attacks against another state…

The term “indirect aggression” was not included in the definition of aggression

adopted by the UNGA. The report of the Secretary General on the Question

of Defining Aggression from 1952 included an extended discussion of indirect

ILC Report 1985, p.42.

O’Connell, Mary E., Niyazmatov, M., What is Aggression? Journal of International Criminal Justice

10 (2012), p.193.

Cassese, A., International Criminal Law, in Evans M.D.,

International Law

, Oxford 2003, p. 747

ICJ Reports, 103-4.

ICJ Reports of the Judgments, Case Concerning Military and Paramilitary Activities in and Against

Nicaragua, Merits Judgement of 27 June 1986, pp. 331-47, 348-50, 543-4.