Countermeasures are unilateral measures adopted by a State (the ‘injured State’) in response to the breach of its rights by the wrongful act of another State (the ‘wrongdoing’ or ‘target’ State) that affect the rights of the target State and are aimed at inducing it to provide cessation or reparations to the injured State (Oxford Public International Law).

Audi alteram partem: Hear the other side (let the other side be heard as well).

Estoppel: A rule of evidence or a rule of law that prevents a person from denying the truth of a statement he has made or from denying facts that he has alleged to exist.