Abstract/Summary

The article examines the international law governing State responses to cyber operations that do not rise to the level of an armed attack under the law of self-defense. Once the operations reach that level, forceful responses are, in certain circumstances, permitted. However, it is generally accepted that force, whether kinetic or cyber in nature, may not be employed in response to operations of lesser severity. Instead, the State is limited to acts in retorsion (unfriendly but lawful) or countermeasures. Countermeasures, which comprise acts that would be unlawful but for the unlawful actions of the other State, are subject to significant conditions and limitations. The article examines them in the cyber context.