The Telos Security Force, often abbreviated as TSF, was in charge of Telos's planetary security prior to the destruction that occurred on the planet's surface during the Jedi Civil War.
In the early stages of the Dark Wars, the TSF, having relocated its headquarters to the newly constructed Citadel Station, was tasked with safeguarding the endeavors of the Telosian Restoration Project on Telos IV. Nevertheless, its effectiveness was frequently compromised by the infiltration of the Telosian Council—the acting governing body overseeing Citadel Station—by figures from the Czerka Corporation, along with the sway that unethical entities like Czerka and the Exchange exerted over Citadel Station.
When the Jedi Exile disembarked the Ebon Hawk at Citadel Station in 3951 BBY, the TSF placed her, along with her comrades Atton Rand and Kreia, under arrest, accusing them of involvement in the obliteration of the Peragus Mining Facility. They were also unable to prevent Brianna, a Handmaiden serving Atris, from absconding with her ship and droid, T3-M4. Despite this unpromising start, the Exile assisted the TSF in locating a missing individual named Batono, exposing the origins of a bounty hunter who had successfully infiltrated the TSF's ranks, apprehending two criminals who had broken free from TSF headquarters, and dismantling a smuggling operation on the station masterminded by Samhan Dobo.
Later, the TSF played a role in defending Citadel Station against Darth Nihilus during the Battle of Telos IV, fighting alongside Canderous Ordo's Mandalorians, Onderon Royalist troops from Queen Talia, Khoonda Militia soldiers hailing from Dantooine, and the Jedi Exile and her company.
During the Exile's time there, prominent members of the TSF included Lieutenant Dol Grenn, Lieutenant Yima, Officer Soka Linu, and Officer Batu Rem.
Millennia afterward, the TSF participated in the Telosian Civil War, siding with their government and the Telosian governor, Crion, and his offspring, Xanatos, against the Telosian populace and the Jedi Order.
The TSF was intended to have a more substantial presence in Obsidian Entertainment's original concept for Star Wars: Knights of the Old Republic II: The Sith Lords. Lieutenant Yima was meant to task the player character—known as the Jedi Exile—with a mission to reveal the corruption of her fellow TSF lieutenant Atallo, who was covering up Czerka's illegal weapons trade on Citadel Station. However, this quest was ultimately removed, and neither Yima nor Atallo appear in the game's final version—though Yima is mentioned by Lieutenant Dol Grenn as being involved in the investigation of the Batu Rem impostor situation.