This article examines the question of whether the right of self-defense under contemporary international law permits a State to react to an immi-nent or potential armed attack carried out by digital means in two circum-stances. First, as an attack occurring in conjunction with, or as an adjunct to, a conventional kinetic armed attack intended to neutralize the target State’s defensive and command and control systems. Second, as an at-tack—independent of any use of kinetic force—intended to cause signifi-cant human casualties, physical damage or large-scale disruption in the tar-get State. While the former scenario is probably considerably more likely than the latter scenario, both will receive attention. The applicable law is the same in either scenario, although there are some potentially significant differences in the modalities of its application, primarily in the identifica-tion of the attacking party and in gauging the level of the response if an attack was conducted wholly in the digital domain.