Counter Terrorist Unit

The Counter Terrorist Unit (also referred to as the Counter Terrorism Unit or CTU) is an intelligence agency in the United States of America which works to investigate and prevent terrorist acts within American borders.

Position Within the U.S. Government
It is not entirely clear what government entity is in charge of CTU, but it may operate under the Central Intelligence Agency. In real life, the CIA does aid counterterrorism efforts by collecting, analyzing, and disseminating information on foreign terrorists. The agency is overseen by the National Security Council, of which the Secretary of Defense is a part. Thus, the Secretary of Defense could have some legitimate authority over a branch of the CIA, as seen in Day 4.

In the book, The House Special Subcommittee's Findings at CTU, CTU is described as a branch of the CIA. The book's description of CTU reads in full:


 * Counter Terrorist Unit (CTU) - Elite branch of the Central Intelligence Agency. The Counter Terrorist Unit operates domestic counter-terrorism divisional headquarters in major U.S. metropolitan areas. The purview of the CTU is to investigate the activities of domestic or foreign terrorists inside America's borders and to prevent terrorist attacks. CTU divisions are made up of investigative agents, intelligence agents, undercover operatives, crack tactical squads for major raids, and special agents to oversee unit activities. CTU is specifically set up to coordinate activities with the Federal Bureau of Investigation, the Justice Department, and the Secret Service as well as local authorities. As a branch of the CIA, CTU operations are overseen by both Congress and the Executive Branch of the federal government.

In the "24: Declassified" novels, there is a note preceding the story that reads in full:


 * After the 1993 World Trade Center attack, a division of the Central Intelligence Agency established a domestic unit tasked with protecting America from the threat of terrorism. Headquartered in Washington, D.C., the Counter Terrorist Unit established field offices in several American cities. From its inception, CTU faced hostility and skepticism from other federal law enforcement agencies. Despite bureaucratic resistance, within a few years CTU had become a major force. After the war against terror began, a number of early CTU missions were declassified. The following is one of them...

Organization and Structure
CTU is based in Washington, D.C. but has many branches across the US. The series follows CTU Los Angeles, which has had to respond to the attempted assassination of Senator David Palmer, a nuclear threat, a deadly virus, the abduction of the Secretary of Defense, and the theft of twenty canisters of weapons-grade nerve gas.

District
District Command oversees a larger region than Division Command, and reports directly to CTU Headquarters in Washington, D.C. When David Palmer flew to Los Angeles on Day 2, he operated out of District Headquarters.

Division
Division Command oversees the Domestic Units in a given region. Division can order a lock-down, which halts all operations within a unit.

Domestic Units
CTU Domestic Units are similar to FBI Field Offices, covering operations within a single city or metropolitan area. Domestic Units report directly to Division Command, but are also subject to evaluation and interference from District. The following is a list of known Domestic Units:


 * CTU Los Angeles: The busiest domestic unit seen on the show, CTU Los Angeles has averted several large-scale terrorist attacks.


 * CTU Austin: Mentioned by Tony Almeida during Day 3. He was being tested by Ryan Chappelle to prove he was competent after being shot earlier in the day. One part of the computer monitor Chappelle had asked him to repeat back to him was an all clear sign from this branch. (Day 3 9:00pm-10:00pm)


 * CTU Boston: Curtis Manning originally worked at CTU Boston.


 * CTU Denver: Secured a vial of the Cordilla Virus. (Conjecture) (Day 3 11:00am-12:00pm)


 * CTU Fairbanks: Helped Jack Bauer run a sting operation on an eco-terrorism group in the graphic novel Midnight Sun.


 * CTU Las Vegas: Found a vial of the Cordilla Virus. (Conjecture) (Day 3 11:00am-12:00pm)


 * CTU New Orleans: Jack Bauer contacted CTU New Orleans in order to check into the sudden disappearance of Robert Ellis, who was murdered during a telephone conversation with Jack and David Palmer.


 * CTU New York: Found a vial of the Cordilla Virus along with the New York Police Department. The vial was attached to a railing but was defused. (Day 3 11:00am-12:00pm)


 * CTU Phoenix: Secured a vial of the Cordilla Virus. (Conjecture) (Day 3 11:00am-12:00pm) CTU Phoenix also sent a helicopter to back up Jack Bauer in the graphic novel One Shot.


 * CTU San Diego: Howard Bern was sent to CTU San Diego to create an alibi after raiding the Chinese Consulate and being identified on surveillance film. (Day 4 2:00am-3:00am)


 * CTU San Francisco: Found a vial of the Cordilla Virus. (Day 3 11:00am-12:00pm) CTU San Francisco also had the closest first-tier Jane Saunders lookalike.


 * CTU Seattle: Found a vial of the Cordilla Virus. (Conjecture) (Day 3 11:00am-12:00pm)


 * CTU Washington: Found 2 vials of the Cordilla virus. (Day 3 11:00am-12:00pm) Alberta Green transferred to CTU Washington after the events of Day 1. (The House Special Subcommittee's Findings at CTU)

''Note: Phoenix is only seen on screen and not spoken. For Seattle, Las Vegas, Denver and Phoenix, it is not stated explicitly that a Domestic CTU Unit found the vials of the virus. However, since these are large U.S. cities, it makes sense that each would have a domestic unit.''