Reports of state-sponsored harmful cyber intrusions abound. The prevailing view among academics holds that if the effects or consequences of such intrusions are sufficiently damaging, international humanitarian law (IHL) should generally govern them—and recourse to armed force may also be justified against states responsible for these actions under the jus ad bellum. This Article argues, however, that there are serious problems and perils in relying on analogies with physical armed force to extend these legal regimes to most events in cyberspace. Armed conflict models applied to the use of information as a weapon and a target are instead likely to generate “legal phantoms” in cyberspace—that is, situations in which numerous policy questions and domestic criminal issues are often misinterpreted as legal problems governed by the IHL framework or the jus ad bellum. This Article assesses this dilemma in the context of four key problem areas relating to dimensions of information: (1) problems of origin, organization, and availability; (2) problems of access and control; (3) problems of exploitation; and (4) problems of manipulation and content.