When one considers the (current) material scope of application of IHL, it becomes clear that transnational armed conflicts do not seem to fall under any of the “definitions” given in treaty law, literature, or jurisprudence. However, the author argues that, in any case, a new regime for a third category is neither necessary nor desirable and explains how the majority of transnational armed conflicts are not regulated by the law on non-international armed conflict, but are governed by the law on international armed conflict. To conclude, he proposes not to focus on the nature of the parties to the conflict, but rather to use the territorial borders of a State as guidance to characterise a conflict as international or as non-international. In the end, what determines whether there is an international or a non-international armed conflict is whether a State uses force against another State. The law of non-international armed conflict would regulate a State’s use of force against an armed group on its own territory, because the conflict itself is non-international in character. However, that same State’s transnational use of force against an armed group on the territory of another State that does not (explicitly) consent to such force is regulated by the law of international armed conflict, because such use of force itself amounts to an international armed conflict.