About: Counterintelligence failures

Countries with major counterintelligence failures are presented alphabetically. In each case, there is at least one systemic problem with seeking penetration agents when few or none may actually have existed, to the detriment of the functioning of the national service involved. Many of the individuals named have separate articles in Wikipedia. The emphasis here is on both national-level counterespionage problems, and how the individuals eluded detection.