Focusing on air and missile warfare, the aim of this article is to discuss rules of customary international law for international armed conflict regarding attacks, understood as "acts of violence against the adversary, whether in offence or in defence". The ambition of this article is humble: to show what seems to be customary law with regard to attacks. The ideal way would be to study actual practise on the battlefield and how the actors justify their actions or their decisions when they choose not to act in a particular way. For practical reasons, a simple methodology is used. Where a particular rule is codified in a widely accepted treaty, it is assumed to reflect customary law unless there is reason to believe that it is rejected by one or more "most affected" States.