Operatives of intelligence services and other covert organizations use the term tradecraft to refer to the techniques of the espionage trade, or the methods by which an agency involved in espionage conducts its business. Elements of tradecraft, in general terms, include the ways in which an intelligence officer arranges to make contact with an agent, the means by which the agent passes on information to the officer, the method for paying the agent, and the many precautions and tactics of deception applied along the way.
Examples of tradecraft can be found in the Ashenden stories, through which British author Somerset Maugham recounted, in fictional form, his experiences as a spy in World War I. In one tale, for instance, Maugham mentioned that Ashenden met an "old butter-woman" regularly in a market in Geneva. The woman was actually an agent of British intelligence who, in real life, passed notes back and forth between Maugham and his superiors in London. This is tradecraft in its simplest form—the employment of someone or something that is not exactly who or what he/she/it seems to be.
Another example of tradecraft in action is the artwork of Robert Baden-Powell who, long before he founded the Boy Scouts, served as a military intelligence officer in the Balkans during the 1890s. In order to sketch enemy fortifications without attracting attention, Baden-Powell adopted the disguise of an entomologist. He made detailed sketches of butterflies and leaves that, on close scrutiny, were revealed to be maps of gun emplacements or trenches.
Tradecraft can also include the many precautions taken to avoid detection in the process of making a drop, or otherwise transferring material between agent and officer, as in Maugham's case of the old butter-woman. In real life, Soviet agent John made his drops using a garbage bag that included bits of recognizable trash—but nothing that would smell strongly, attract animals, or cause damage to the documents and other important materials he left for his KGB handlers.
█ FURTHER READING:
Carl, Leo D. The CIA Insider's Dictionary of U.S. and Foreign Intelligence, Counterintelligence, and Tradecraft. Washington, D.C.: NIBC Press, 1996.
Melton, H. Keith. The Ultimate Spy Book. New York: DK Publishing, 1996.
Nash, Jay Robert. Spies: A Narrative Encyclopedia of Dirty Deeds and Double Dealing from Biblical Times to Today. New York: M. Evans, 1997.
Polmar, Norman, and Thomas B. Allen. Spy Book: The Encyclopedia of Espionage. New York: Random House, 1998.
Cambridge University Spy Ring
Dead Drop Spike
Hanssen (Robert) Espionage Case
Walker Family Spy Ring
"Tradecraft." Encyclopedia of Espionage, Intelligence, and Security. . Encyclopedia.com. (March 20, 2019). https://www.encyclopedia.com/politics/encyclopedias-almanacs-transcripts-and-maps/tradecraft
"Tradecraft." Encyclopedia of Espionage, Intelligence, and Security. . Retrieved March 20, 2019 from Encyclopedia.com: https://www.encyclopedia.com/politics/encyclopedias-almanacs-transcripts-and-maps/tradecraft