Retorsion
Retorsion (from French: rétorsion, from Latin: retortus, influenced by Late Latin, 1585–1595, torsi, a twisting, wringing it), a term used in international law, is an act perpetrated by one nation upon another in retaliation for a similar act perpetrated by the other nation. A typical example of retorsion is the use of comparably severe measures against citizens of the foreign nation found within the borders of the retaliating nation after the foreign nation has engaged in similar acts.