In between those computer network operations taken outside of armed conflict evaluated above, and those taken within, which will be examined later on, there remain those operations which may be qualified as legitimate uses of force under the ius ad bellum paradigm. This is the case for those operations that are taken within the ambit of the right of self-defence as enshrined in Article 51 UN Charter, which together with enforcement actions decided upon by the UN Security Council under Chapter VII UN Charter and the – now generally considered obsolete – enemy State clauses, form the only generally accepted exceptions to the prohibition of the use of force.

The following section will first determine the possibility of computer network operations giving rise to the right of self-defence by the victim State, followed by an evaluation of them as enforcement measures authorised by the UN Security Council under Chapter VII UN Charter.

THE RIGHT OF SELF-DEFENCE

The history of the right of self-defence has to be read together with the prohibition on the use of force. As the freedom of States to wage war was for a long time seen as an essential right, there was no need for a right of self-defence. It was only when the prohibition of war and later of the use of force was recognised, that a right of States to defend themselves against armed attacks in breach of the aforementioned principles was regarded as a necessary exception to the general prohibition on the use of force. In order to abide by the prohibition on the use of force, States needed to justify the use of forceful military countermeasures. But even before the need to legally justify the use of force in the 20th century, States used the argument of self-defence – either for political reasons, or in order to justify acts in situations short of war, such as in the Caroline Case. As the concept of self-defence has long been known under national laws, especially criminal law, international law could have recourse to a considerable foundation of the underlying principles developed in the national fora.