States across the globe are increasingly involved in violent conflicts with non-state groups both within and across borders. This new situation challenges the classic distinction in international humanitarian law between international and noninternational armed conflicts. However, the changing face of warfare does not diminish the importance of IHL. The essence of this body of law - to protect civilians and persons hors de combat and to lessen unnecessary harm during armed conflict - remains the same. The applicability of IHL must therefore be determined according to objective criteria and must not be left to the discretion of the warring parties. This article seeks to conceptualize the notion of armed conflict and examines the extent to which the existing body of humanitarian law applies to the new asymmetrical conflicts. It finds that the definition given by the ICTY Appeals Chamber in its Tadic´ Decision on Jurisdiction, which was taken up by Article 8(2)(f) of the Rome Statute, is a useful starting point for an analysis of the "triggering mechanism' of international humanitarian law in asymmetrical conflicts.