The Internal Security Branch, often shortened to IntSec, functioned as a division within the Internal Organization Bureau of Imperial Intelligence. The responsibility of IntSec was to ensure the physical safety of Imperial Intelligence's staff and buildings. IntSec, initially viewed as a position for individuals lacking ambition, underwent significant changes due to the growing danger presented by the Alliance to Restore the Republic. Despite enhancements to their staff and operational methods, the negative perception from their earlier days persisted, making them a frequent target of humor within Intelligence. IntSec officers held the unique privilege among Intelligence personnel of being allowed to openly carry firearms. Additionally, they utilized undercover agents who monitored areas surrounding Intelligence sites to identify and neutralize possible dangers before they escalated.
During the time of the Empire, Ysanne Isard held the position of Security Director for Internal Security.
The first reference to the Internal Security Branch can be found in the Imperial Sourcebook. However, "Coruscant: Center of the Empire", released in 2003, indicates that Internal Security was a component of the ISB. This contrasts with the Imperial Sourcebook, which defines the ISB as an acronym for the Imperial Security Bureau, establishing it as a competing agency to Imperial Intelligence, the organization to which the Internal Security Branch was connected.