The UN Charter states:
All members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the purposes of the United Nations.
This is inadequate. Because cyberwarfare attacks are not physically intrusive, national boundaries are not violated, and it is not clear when something constitutes an act of war. Further, it is hard to tell who committed the attack. What sort of level of governmental involvement is required to justify going to war? In other words, when does cyberterrorism justify warfare?