This essay requires a solid analysis of Art 51 UN Charter. First, you should clarify the basic rule under Art 2(4) UN Charter which generally prohibits the use of force, thereafter justifying two particular exceptions—that is, self-defence under Art 51 and Security Council authorizations under Art 42 UN Charter. From there, you should develop what constitutes an armed attack in accordance with the stipulations of the ICJ in the Nicaragua case, as well as other ICJ cases which have been mentioned in this chapter. You should note in your analysis the possibility of agency in the law relating to the use of force and particularly the attribution of the armed attack. Then, you need to make reference to the Oil Platforms case and explain whether the ICJ departed from its findings on the ambit of ‘armed attack’ in relation to the Nicaragua case. Thereafter, you should discuss the existence of self-defence under customary international law, which is found in the phrase ‘inherent’ of Art 51 UN Charter. In particular, you need to explain whether pre-UN Charter or post-UN Charter instances of attacks, such as imminent threats, are sufficient to trigger the right to use force even though they do not seemingly satisfy the criteria for an armed attack. You may, eventually, want to include in your discussion whether the devastating activities of non-State actors such as terrorists or guerrilla groups can commit an armed attack or whether this is only confined to States.