Office of Naval Intelligence

The Office of Naval Intelligence, often abbreviated as ONI (pronounced as /oʊni/), is the intelligence service of the UNSC Navy. Its formal name is the UNSC Military Intelligence Division.

Introduction
The Office of Naval Intelligence is a division of the UNSC Navy that is responsible for UNSC intelligence, including electronic intelligence, naval intelligence, counter-espionage, and propaganda.

Although it is under the jurisdiction of the Navy, ONI appears to report directly to HIGHCOM, and is responsible for intelligence matters that are handled across the UNSC and are not restricted solely to the Navy. As such, ONI employs members of other military branches, or even civilians, to complete the Division's shadowy work.

Many of its functions and subdivisions, like the Beta-5 Division and the SPARTAN-III Program, are enigmatic, and its personnel are regarded as mysteries to mainline naval officers, who often refer to ONI personnel, especially officers, as "spooks". ONI personnel appear to enjoy a significant amount of liberty in their duties, oftentimes violating moral boundaries to achieve their ends or acquiring a vast amount of UNSC resources.

Operations
The Office of Naval Intelligence is often isolated from other UNSC branches and often carries out its operations in isolation, at times even going against protocols and laws to complete top-secret missions. However, they appear to have a surprisingly large amount of military equipment for an intelligence service, and have a strong fleet presence, possibly because of ONI's association with the Navy. The Office of Naval Intelligence possesses a destroyer-class prowler starship, the, which is used as a command vessel and a secure conference location. ONI also maintains the UNSC's force of Prowler craft, a major source of Covenant deployment intelligence, under the UNSC Prowler Corps. ONI also operates field intelligence, with units such as ONI Recon 111 liaising with mainstream UNSC military units.

However, intra-ONI dynamics are often tense with severe competition amongst its own personnel. Personnel are oftentimes heavily scrutinized by their commanding officers and are given notably low room for errors under intense pressure of demotion or otherwise.

Section Zero
The most secretive section of ONI. Almost no one knows that it even exists actually, let alone exactly what they do in the supposed high chain of command. From the records of an AI named Melissa, it is thought to be ONI Internal Affairs, charged with rooting out and eliminating illegal programs. They are very secret in their work.

This section has gained notoriety as the section that has sealed SPARTAN-I Program files, including Avery Johnson's.

Section One
The main intelligence-gathering section, and the foremost provider of electronic intelligence for the UNSC. Covenant ship movements and force deployment, evacuation notices for colonies, deletion of data for secrecy purposes, and much more are all done by Section 1.

Section Two
The propaganda branch of ONI. They handle communication to and from colonies to reduce the level of rumors and information that would cripple morale. They were responsible for going public with the SPARTAN-II program to boost morale through the UNSC ranks. Even after the release of this information to the public, the Spartans were still viewed as near-mythological figures. Most Marines and ODSTs didn't believe they even existed until they saw them for themselves. Section II feared the fact that the discovery of Spartans dying would cripple morale. Due to this, the Spartans are always listed as MIA or WIA instead of KIA upon death to keep morale up in the UNSC and maintain the belief that Spartans never die.

Section Three
The top-secret projects division of ONI. They are responsible for the SPARTAN-II project, the NOVA project, and many other "black ops" programs. The secrets possessed by ONI are the key to Earth's continued survival, for the Covenant cannot be beaten with military forces alone. Though a few of Section III's programs are well known and prominent for their success and diverse victories, the Marines and brass of the UNSC treat most with contempt. This is especially true of the capability of the Spartans, who are generally regarded as "freaks" by the other Humans in the Armed Service of the United Nations Space Command. The Beta-5 Division is the sub-cell of Section III that operates the SPARTAN-III project. The Spartan-III project was even kept secret from the vast majority of section 3. This is not particularly rare, as section 3 is a large division with various production cells. We can see this, as some groups were tasked with MJOLNIR and others with the actual Spartan-II program.

UNSC Prowler Corps
The ONI branch that handles the Prowlers and their electronic intelligence gathering.

ONI Signal Corps
The Signal Corps is tasked with broadcasting radio signals in order to confuse Covenant Fleet and troop movements, diverting attention from UNSC Colonies who are evacuating.

Known ONI Personnel

 * Vice Admiral Margaret O. Parangosky
 * Rear Admiral Rich
 * Captain Gibson
 * Colonel James Ackerson
 * Colonel Herzog
 * Commander J. G. Ortega
 * Lieutenant Commander Fhajad-084
 * Lieutenant Commander Jilan al-Cygni
 * Major Standish
 * Lieutenant Elias Haverson
 * Lieutenant Wagner
 * Corporal Jason Morelli
 * Codename: SURGEON
 * Codename: COALMINER
 * Kowalski
 * Lawson
 * Rani Sobeck (Section One)
 * Major Akio Watanabe
 * Corinthia Hansen
 * Josh Smith
 * Captain Veronica

ONI Ships

 * STARS
 * - Retired
 * UNSC Prowler- Flagship
 * - Retired
 * Stealth Cruiser
 * Stealth Cruiser

Reach

 * CASTLE Base
 * ONI Medical Facility
 * HIGHCOM Armory Omega

Onyx

 * Zone 67
 * Camp Currahee

Earth

 * Chawla Base
 * HighCom Facility Bravo-6
 * B5D
 * Alpha Base

ONI Units

 * ONI Recon 111

NavSpecWar

 * Beta-5 Division
 * Spartan-II
 * Spartan-III Battalion

Trivia

 * The Office of Naval Intelligence is a real life existing organization within the U.S. Navy.
 * ONI operatives are referred to in slang as "spooks".
 * ONI is a reference to an older Bungie game called Oni.
 * Oni means demon in Japanese.
 * ONI's motto, "Semper Vigilans", is also the motto of the United States Civil Air Patrol Air Force Auxiliary.
 * ONI's insignia features the all-seeing eye, a nod to ONI's line of work.
 * It appears that ONI's policy regarding the Spartans to register them as MIA, despite the fact that they are dead, however, apparently does not apply to Master Chief, as he is ironically listed as KIA, even though he survives.
 * ONI reactors are available in the Halo Wars campaign. They're all abandoned.