The outbreak and continuation of armed hostilities can sometimes cause harm to bordering States not directly involved in the hostilities. This has occurred in many military operations conducted during the last few decades. The scope of the provisions relating to the protection of the environment during armed conflict appears to be strictly limited to the territory in which the operations are taking place. It is therefore important to determine the extent to which a belligerent State at the origin of acts that have had devastating consequences on the territory of one or more States not involved in the conflict can be held internationally responsible for those acts based on the principle of international liability for injurious consequences arising out of acts not prohibited by international law, which is still under discussion. The argument put forward in this article is based on the hypothesis that this principle is at least implicitly recognized when it comes to environmental damage caused in the context of an armed conflict. In our view, this is grounded both in the principle of the inviolability of neutral States and in the no-harm principle, whereby a State cannot use its territory in a way that is harmful to other States not involved in the armed conflict. These principles are based on the notions of fault and risk.