In espionage jargon, a mole (also called a penetration agent, deep cover agent, or sleeper agent) is a long-term spy (espionage agent) who is recruited before he has access to secret intelligence, and subsequently works his way into the target organization. However it is popularly used to mean any long-term clandestine spy or informant within an organization, whether government or private.
The term was introduced to the public by British spy novelist John Le Carré in his 1974 novel Tinker, Tailor, Soldier, Spy and has since entered general usage, but its origin is unclear, as well as to what extent it was used by intelligence services before it became popularized. Le Carré has said that the term mole was actually used by the Soviet intelligence agency KGB, and that a corresponding term used by Western intelligence services was sleeper agent. While the term mole was applied to spies in the book Historie of the Reign of King Henry VII written in 1626 by Sir Francis Bacon Le Carré has said he did not get the term from that source.
A mole may be recruited early in life, and may take decades to get a job in government service and reach a position of access to secret information before he becomes active as a spy. Perhaps the most famous examples of moles are the Cambridge Five, five upper-class British men recruited by the KGB as left-wing students at Cambridge University in the 1930s who later rose to high levels in various parts of the British government. By contrast, most espionage agents, such as CIA Director of Counterintelligence Aldrich Ames and FBI agent Robert Hanssen who spied on the US government for the KGB, are either recruited or offer their services as spies after they are in place as members of the target organization.
Because their recruitment occurred in the remote past, moles are difficult for a nation's security services to detect. The possibility that a top politician, corporate executive, government minister, or officer in an intelligence service could be a mole working for a foreign government is the worst nightmare of counterintelligence services. For example, James Angleton, director of counterintelligence for the CIA between 1954 and 1975, was reportedly obsessed with suspicions that the top levels of Western governments were riddled with long-term communist agents, and accused numerous politicians such as Henry Kissinger, Lester Pearson, Pierre Trudeau, and many members of Congress before he was removed in 1975. Fears of such moles in prominent positions in American life led to overreactions such as McCarthyism.
Moles have been featured in numerous espionage films, television shows, and novels.
Reason for using moles 
The most common procedure used by intelligence services to recruit agents is to find the location within the foreign government or organization of the information they want (the target), find out which people have access to it, and attempt to recruit one of them as a spy (agent) to obtain the information. However, the people with access to top secret government information, government employees with high security clearances, are carefully monitored by the government's security apparatus for just this sort of espionage approach, so it is difficult for a representative of the foreign intelligence service to meet with them clandestinely to recruit them. Private organizations such as large corporations or terrorist groups have similar security monitors. In addition, the security clearance process weeds out employees who are openly disgruntled, ideologically disaffected, or otherwise have motives for betraying their country, so persons in these positions are likely to reject recruitment as spies. For these reasons, some intelligence services have tried to reverse the above process, and recruit potential agents first, and have them conceal their allegiance, and pursue careers in the target government agency in hopes that they can reach positions of access to desired information.
Because the spy career of a mole is such a long-term one, sometimes occupying a majority of a lifetime, persons who become moles must be highly motivated. One common motivation is ideology (political convictions). During the Cold War a major source of moles in Western countries was so-called "fellow travellers", Western citizens who in their youth in the 1920s to 1940s became disaffected with their own governments and sympathetic to world Communism without actually joining the Communist party.
See also 
- Agent of influence
- Double agent
- Economic and Industrial Espionage
- Sleeper agent
- Insider threat
- The Mole (TV series)
- Smith, W. Thomas (2003). Encyclopedia of the Central Intelligence Agency. Manhattan, New York City, USA: Infobase Publishing. p. 171. ISBN 9781438130187. OCLC 586163250. Retrieved August 26, 2012.
- IBP USA, USA International Business Publications (February 7, 2007). US Military Intelligence Handbook, Vol. 1 (6th ed.). Washington, D.C., USA: International Business Publications. p. 29. ISBN 9781433056833. Retrieved August 26, 2012.
- Green, Jonathon (March 28, 2006). Cassell's Dictionary of Slang: A Major New Edition of the Market-Leading Dictionary of Slang (2nd, revised ed.). New York City, New York, USA: Sterling Publishing. p. 953. ISBN 9780304366361. OCLC 62890128. Retrieved August 26, 2012.
- Carlisle, Rodney P. (April 1, 2003). Complete Idiot's Guide to Spies and Espionage (illustrated ed.). Indianapolis, Indiana, USA: Alpha Books. p. 142. ISBN 9780028644189. OCLC 52090218. Retrieved August 26, 2012.
- Shapiro, Fred R. (Oct 30, 2006). The Yale Book of Quotations (illustrated ed.). New Haven, Connecticut, USA: Yale University Press. p. 448. ISBN 9780300107982. OCLC 66527213. Retrieved August 26, 2012. "According to the Oxford English Dictionary "it is generally thought that the world of espionage adopted [the term mole] from Le Carré, rather than vice versa."
- Le Carré, John; Bruccoli, Matthew J; Baughman, Judith (2004). Conversations with John le Carré (illustrated ed.). Jackson, Mississippi, USA: University Press of Mississippi. pp. 33–34. ISBN 9781578066698. OCLC 55019020. Retrieved August 26, 2012. "interview with Le Carré in Melvyn Bragg The Listener, January 22, 1976 BBC1, (reprint)"
- Further reading
- Staff (November 29, 2009). Why Do We Say It?: the stories behind the words, expressions and cliches we use (reissue ed.). Secaucus, New Jersey, USA: Castle Books. ISBN 9781555210106. OCLC 237155763. Retrieved August 26, 2012.