The ONI Covert Operations Unit was the Office of Naval Intelligence's primary attack force. Their existence was a tightly kept secret, and they were known to only a few members of the UNSC High Command. Although Lord Hood despised them for their missions' tendencies to be targeting members within the UNSC, he recognized the need for such a force as a means of policing high ranking and otherwise untouchable officials. The COU's actions were directed by Vice Admiral Parangosky, and they were led in the field by Captain Tiberius Lierne, an ONI agent whose savagery and efficiency had brought him to the attention of his superiors.