The intelligence branch of Starfleet, responsible for gathering information on hostile powers and running covert missions.
Starfleet Intelligence gathers and analyses information about rival powers such as the Cardassians, the Romulans and the Dominion, and its reports are cited by Starfleet officers throughout the 24th-century series. It also runs covert operations, sometimes placing officers deep inside dangerous organisations.
In the Deep Space Nine episode Honor Among Thieves, Miles O'Brien goes undercover for Starfleet Intelligence inside an Orion Syndicate cell. The agency is distinct from Section 31, the rogue organization that operates outside Starfleet's oversight and sometimes poses as legitimate Starfleet authority.