Security, also referred to as Alliance Security, functioned as a division within the Counter-Intelligence section of Alliance Intelligence. The primary function of Security was to enlist agents and strategically position them throughout the Alliance's various departments. The exact quantity of operatives and the specifics of their duties within Security remained a highly protected piece of information, with even Chief of State Mon Mothma lacking comprehensive knowledge of their actual capabilities. As a cover, two Security agents infiltrated Mon Mothma's personal team, posing as assistants. In situations where a Security operative suspected someone of being an Imperial Intelligence agent, the case would be transferred to Retrieval for further investigation and legal proceedings.
Following the events of the Battle of Endor, Tycho Celchu received protection from Alliance Security personnel because General Salm harbored suspicions that he might be a mole for the Imperial forces. Before the Battle of Coruscant, Alliance Security provided assistance to Rogue Squadron by orchestrating the release of multiple known offenders from the penal colony of Kessel. These individuals were subsequently transported to Coruscant to divert the attention of Imperial troops, facilitating the New Republic's successful capture of the capital.