Counterintelligence is an ability that is exclusive to Spies and Scouts. It is used to kill enemy spies and remove informers from buildings.
Unlike spies, scouts will automatically use Counterintelligence on enemy spies whenever they see one. This makes scouts doubly useful as defense against bribery, serving as both a mobile detector and a quick spy killer.
The range of Counterintelligence is increased by the Strategy line of research.