A route with changes of direction and means of transport, used by a person to check whether they are being followed.
Description based on Crypto Museum. The International Spy Museum calls such measures dry cleaning – actions an agent takes to find out whether they are under surveillance.1,2
On the other side is counterintelligence, which conducts the surveillance. An example from the FBI files: on 13 October 1993 agents watching CIA officer Aldrich Ames spotted a chalk mark he had left on a mailbox – a signal for a meeting with his Russian handler in Bogotá; on 1 November the FBI watched both of them there. Ames was arrested on 21 February 1994.3
Sources
- Crypto Museum, Glossary of covert expressions
- International Spy Museum (Washington, DC), Language of Espionage (glossary)
- FBI, Famous Cases: Aldrich Ames
Checked: 4 November 2026