The overall effectiveness of Technical Surveillance Countermeasures (TSCM) strategy is significantly based on Operational Security (OPSEC) measures.
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(1) TSCM services are specialized counterintelligence investigations and as such, are particularly vulnerable to compromise. All commands which receive TSCM services must implement OPSEC measures to ensure the success of the countermeasures effort. Assume, until the survey indicates otherwise, that a technical surveillance device is actually in place.
(2) Should discussions concerning pending support take place within the space, the device would most likely be removed prior to the survey and later reinstalled, or simply deactivated remotely. Under such circumstances, the probability of locating a technical surveillance device is diminished greatly. For this reason, no discussion or verbal comments concerning pending TSCM support shall take place in the spaces of concern, nor shall discussions or verbal comments take place during the survey.
(3) Telephone requests or discussions of scheduled TSCM support are considered compromising unless conducted over secure voice systems outside the facility to be serviced. Similarly, e-mail messages referencing anticipated or occurring TSCM services originating from or going to the concerned spaces will also be considered a compromise of the services.
Source: United States Marine Corps: Technical Surveillance Countermeasures (TSCM) program, I MEFO 5511 (2011.)
