Signals intelligence by alliances, nations and industries

Signals intelligence by alliances, nations and industries comprises signals intelligence (SIGINT) gathering activities by national and non-national entities; these entities are commonly responsible for communications security (COMSEC) as well. Many US and allied SIGINT activities are considered Sensitive Compartmented Information (SCI) and carry the special security marking "HANDLE THROUGH COMINT CHANNELS ONLY", which is abbreviated as the suffix CCO to the security classification.

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