Internal security turrets were part of a leviathan gunship's internal defense system. They were used in conjunction with heavily armed DRDs to defend the gunship. The turrets were mounted throughout the ship and could drop down at a moment's notice, but they were most commonly seen around the command center.
When Alcar interacted with the gunship neural implant on Talyn, Bialar Crais commanded the gunship to fire his internal turrets on the Scarran, killing the beast. ("Infinite Possibilities - Icarus Abides")