sleeper terrorist

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a terrorist who is not currently active but assumes a guise in order to be in position, unsuspected, for future terrorist activities
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“Was” is used for the indicative past tense of “to be,” and “were” is only used for the subjunctive past tense.
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012


What is a sleeper cell?

A sleeper cell is a group of operatives, spies or terrorists, living in secret among a targeted community waiting for instructions or an opportunity to act.

Where did the term sleeper cell come from?

The idea of a singular sleeper agent stretches back to at least 1948, when Danish writer Ib Melchior published a short story called “Sleeper Agent.” Two years later, an article by J. Edgar Hoover in The Coronet, titled “The Underground Tactics of the Communists” described Soviet spies “going underground—for special assignment as a ‘sleeper agent.’”

Allison Ind’s 1963 Short History of Espionage described a sleeper agent as “one inserted into an unsuspecting community in time of peace to wreak destruction with the onset of war.” In fact, during the Cold War, the Soviet Union had sleeper agents stationed in Washington DC, ready to cut off the city’s electricity in the event of an outbreak in hostilities. Sleeper agents remain dormant or inactive until the time to act, doing no other espionage work.

A group of sleeper agents is a sleeper cell. The term goes back at least to a 1968 New York Times book review. According to Google’s Ngram Viewer, the term had a spike in use in books between 1975 and about 1982. Incidentally, Ib Melchior expanded his short story “Sleeper Agent” into a novel of the same title in 1975.

Over time, sleeper cell has been used less to describe espionage and more to describe terrorism. For instance, US News and World Report published the headline “The French nab an Iranian ‘sleeper cell.’ (terrorist group)” in January 1987.

The use of sleeper cell to refer to a terrorist group took off in 2001, following the September 11 attacks carried out by members of the terror group al-Qaeda living in the United States. Former State Department Agent Scott Stewart pointed out in an article for the think tank Stratfor (formerly Strategic Forecasting), that the September 11 terrorists were not a sleeper cell by the classic definition, because they began planning and acting shortly after entering the U.S. That said, the term has been frequently used in recent years to describe any terrorist group living secretly among its target population.

Shortly after the September 11 attacks, four Middle Eastern men were arrested in Detroit and charged with planning a terror attack. Media reports referred to the men as a sleeper cell, as did court documents. Two of the men were convicted, but the convictions were later overturned.

The broader use of the term is reflected in the TV show Sleeper Cell, which ran for two seasons from 2005–2006. The show focused on a group of terrorists living in secret in Los Angeles.

Examples of sleeper cell

“The Islamic State group, also known as ISIS, has been calling on supporters around the world to set up sleeper cells since at least August 2014, after a US-led airstrike campaign began bombing militant targets.”
—Michael Kaplan, “What Is An ISIS Sleeper Cell? After Paris Attack, Concerns Mount That Islamic State Operatives Could Export Terror,” International Business Times (November 16, 2015)

“But, he pointed out, what may have ‘looked like a standard kids show’ on the surface in fact provided ‘this early Cold War representations of Russians [who] had infiltrated’ quiet corners of the United States. Rocky and Bullwinkle was set in Frostbite Falls, Minnesota. ‘Boris and Natasha were, to some extent, the first sleeper cell,’ Thompson said.”
—Jessica Goldstein, “The Russians are coming: Unpacking America’s favorite villain,” ThinkProgress (April 20, 2017)


This content is not meant to be a formal definition of this term. Rather, it is an informal summary that seeks to provide supplemental information and context important to know or keep in mind about the term’s history, meaning, and usage.

How to use sleeper terrorist in a sentence