"The most controversial revelation in Sentry Eagle might be a fleeting reference to the NSA infiltrating clandestine agents into “commercial entities.” The briefing document states that among Sentry Eagle’s most closely guarded components are “facts related to NSA personnel (under cover), operational meetings, specific operations, specific technology, specific locations and covert communications related to SIGINT enabling with specific commercial entities (A/B/C).”
It is not clear whether these “commercial entities” are American or foreign or both. Generally the placeholder “(A/B/C)” is used in the briefing document to refer to American companies, though on one occasion it refers to both American and foreign companies. Foreign companies are referred to with the placeholder “(M/N/O).” The NSA refused to provide any clarification to The Intercept."