ONI Security is the Office of Naval Intelligence's primary security force. While ONI manages their operations, they are actually placed under the jurisdiction of Naval Special Warfare. Soldiers within ONI Security are recruited from the UNSC Army and Marine Corps.
- Main article: Raid on Ivanoff Research Station
On July 24, 2557, Ivanoff Research Station came under attack by the Covenant Remnant and the Ur-Didact's Prometheans. The ONI Security on station were the first to respond to the threat. When John-117 arrived, they assisted him to the best of their ability. In the end, all the security personnel on the station were either killed by the Covenant or Composed by the Didact.