In the context of international law, one of the pressing questions is whether cyber warfare fulfils the definition of armed conflict. Unquestionably, there need to be parties to the conflict. But if we have no knowledge of the source of a cyber attack, then we may be obstructed from determining the conflict, from applying the rules, and most importantly, from having any form of accountability. We then still need to identify the existence of force between States, which is usually understood to mean armed force. Under ius ad bellum and depending on their precise nature and consequences, cyber attacks may be a violation of the prohibition on use of force or of non-intervention, but this may be too low a threshold to necessarily determine existence of armed conflict. Under ius in bello, the law makes reference to ‘hostilities’ and to ‘attacks’. Hostilities can encompass more than single acts of violence, but the latter are usually expected to be part of the situation. As for ‘attacks’, these are traditionally understood to include an element of armed violence. However, it seems fair to assume that the primary focus was on the fact that the attacks were acts designed to cause physical harm, whether human casualties or physical damage and destruction. As such, it could be argued that cyber warfare which has these same effects, could be considered as equivalent to the type of violence envisaged to exist under the ius in bello.