Professional intelligence personnel who were deployed in the West during the Cold War under long-term commercial or other covers. They were vulnerable to arrest but because they operated in isolation from diplomatic premises, they were rarely the subject of the routine surveillance intended to identify intelligence personnel. The discipline of illegals was perfected by the KGB, which ran them as Line X personnel through Directorate N, an organization within the First Chief Directorate dedicated to the training, management, and support of illegals. Extremely difficult to detect, illegals invariably transited through a third country before reaching their target environment and often waited for years, developing a “legend,” before they were activated to perform particular clandestine duties.
The senior illegal in any territory was designated the illegal rezident and fulfilled much the same task as his legal counterpart who enjoyed diplomatic immunity. During the Cold War, only two illegal rezidents were ever caught: Willie Fisher in the United States in June 1956, and Konon Molody in London in January 1961. Both were convicted of espionage and given long prison sentences, but were subsequently released in spy swaps.