Moles in espionage

A mole is a person who spends a long period of time establishing a position of trust within an institution in order to secretly further the interests of a rival organization or government. Moles are a basic tool of espionage.
The collapse of the USSR and the Warsaw Pact, and the accessibility of the archives of the different secret services in its various republics, has led to the unmasking of former communist moles in Western countries.
(E) Emanations of other problems