While the rules of the jus in bello are generally operative in cyberspace, it appears to be problematic to apply the fundamental principle of distinction because of the systemic interconnection of military and civilian infrastructure in the cyber realm. In this regard, the application of the accepted legal definition of military objectives will make various components of the civilian cyber infrastructure a legitimate military objective. In order to avoid serious repercussions for the civilian population that might follow from this inherent interconnectedness, different concepts are analysed that could provide potential solutions for a clearer separation of legitimate military targets and protected civilian installations and networks. The approaches discussed range from the exemption of central cyber infrastructure components that serve important civilian functions, to the creation of ‘digital safe havens’ and possible precautionary obligations regarding the segregation of military and civilian networks. As a solution, the authors propose a dynamic interpretation of the wording ‘damage to civilian objects’ within the principle of proportionality of Article 51(5)(b) of Additional Protocol I, an interpretation that would comprise the degradation of the functionality of systems that serve important civilian functions.