Countermeasures must also be distinguished from actions taken based on a plea of necessity (Rule 26). The former differ from the plea in two main ways. First, there must be an underlying internationally wrongful act to justify countermeasures, whereas necessity has no such condition precedent. In other words, the act that precipitates a countermeasure must be attributable to a State, while acts pursuant to the plea of necessity may be taken in response to the cyber operations of non-State actors (or even when the author of the act is unidentified). Second, mere international wrongfulness
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