“Retaliation” and “revenge” have no legitimacy in international law. There is, however, the concept of “lawful reprisal,” which consists of acts which normally would be illegal, but are taken in response to prior illegal attacks. A reprisal can only be taken as a last resort in self-defense, and must be executed with the objective of ensuring future compliance with legal norms. Steven Ratner does not approve of the term reprisal, and instead stresses the importance of self-defense: “The violation of international humanitarian law by one side in an armed conflict does not justify its violation by the other.”