The United Nations Anti-Terrorist Coalition (UNATCO) is a branch of the United Nations supposedly created as a response to the growing threat of international terrorism. It is actually a police force for Majestic 12 and is used as their main influence on the population of the United States. Many of the major characters were members of UNATCO, including the Denton brothers, Jaime Reyes, Sam Carter, Alex Jacobson, Anna Navarre and Gunther Hermann, but, depending partially on the player's actions, they died, were kicked out or defected, due directly or indirectly to UNATCO's conspiracy with Majestic 12. The headquarters was established in an old bunker on Liberty Island, supposedly as a response to the bombing of the Statue of Liberty. At first, this was believed to be a Silhouette attack, but as one progresses through the game, one increasingly realises that Majestic 12 may have been the culprit after all.
The director of UNATCO in the first few levels of the game is Joseph Manderley, but after the defection of both Denton brothers, Walton Simons takes full charge of the organization, due to Manderley's inability to control his subordinates. To further compound the conspiracy between UNATCO and MJ12, there is a vast MJ12 research facility located beneath the UNATCO HQ bunker. The entrance to this facility is located behind UNATCO's medical lab. On your visits to UNATCO HQ prior to being held prisoner in the MJ12 complex, this entrance is inaccessible, but upon your escape from the complex, the door can be opened.
From what can be gleaned from the backstory of Deus Ex, UNATCO was formed in the early 21st century. It may be the case that Task Force 29 is a progenitor for what became UNATCO with Task Force 29 Director Joseph Manderley later becoming Director of UNATCO.
The exact date of the genesis of UNATCO is unclear although several of the game's characters have worked for the organization for many years, including Sam Carter, Paul Denton, Anna Navarre and Gunther Hermann. The game's protagonist, 23 years old in the game, also mentions adolescent dreams of working for the organization.
Before the events of Deus Ex, UNATCO with the collaboration of Interpol locate and storm the Knights Templar headquarters in Paris and dissolve the organization, removing a rival to the Bob Page controlled Majestic 12. Later, when the Statue of Liberty is bombed, UNATCO (under the orders of Majestic 12) produces false evidence to blame the Silhouette. Before this UNATCO was not permitted to operate within the United States, however this false flag operation provided the political leverage for Illuminati controlled President Philip Riley Mead to welcome UNATCO on to US soil.
In the intro of the game, Walton Simons says that UNATCO was "formed by executive order"; however, one book and one newspaper mention a "UNATCO Charter", which would have to be a treaty like the UN Charter.
At the start of the game, it appears that UNATCO's intent is to defeat global terrorism perpetrated by groups like the National Secessionist Forces (NSF) and Silhouette. But as the story progresses the player discovers that the director, Joseph Manderley, is the pawn of a secret conspiracy that calls itself Majestic 12. As a consequence, UNATCO is just a single tool for global hegemony. By the end of the game the player works actively against the covert operations of UNATCO and Majestic 12.
UNATCO's American base is in the location of an underground bunker beneath Liberty Island. Deeper beneath the base are the Majestic 12 laboratories and prison. Several UNATCO agents have access to the MJ12 facilities beneath the Liberty Island UNATCO base, including Manderley, Anna Navarre, Paul Denton and Gunther Hermann.
The player uncovers financial links that bind UNATCO to Walton Simons, head of the FEMA and a key leader of Majestic 12. UNATCO does much of MJ12's dirty work, including the dispersal of biological warfare agents against the general population, and military suppression of any peaceful or military resistance to UNATCO member governments. UNATCO's establishment as a permanent military police in the United States in the year 2051 is the first open display of MJ12's ambition for a world government. As Deus Ex begins, MJ12 operates openly as a military occupier in certain urban sectors of France. The game does not make it clear whether Majestic 12's open operations there are due to government complicity or military takeover. It is also made clear that the persistence in France of the strongest remnants of the Bavarian Illuminati necessitates Majestic 12's open military displays - much of MJ12's effort in Paris centers on the eradication the French Illuminati and their allies, Silhouette.
With the onslaught of The Collapse perpetrated by JC Denton at the end of Deus Ex, UNATCO, along with most other global entities, is portrayed in the game's sequel, Deus Ex: Invisible War, as having effectively ceased to exist. The old Liberty Island UNATCO base makes a cameo appearance at the end of Invisible War as it is used by JC Denton to store the dormant Aquinas protocol, though by the year 2072 when the game is said to take place, the complex is effectively a ruin.
Although ostensibly an agency of the United Nations, a large part of UNATCO's budget comes from Walton Simons, whose covert transfers permit the acquisition of modern body armor, assault rifles, and other militaryy hardware. The fact is classified and known only to UNATCO's accounting department and the highest echelons of command. Regular troops have standing orders to destroy any evidence of these transfers, with the common explanation being that Simons is a philantropist and "good to the bone". When Paul Denton defected and delivered UNATCO's accounting information to the NSF,  UNATCO's assault on the base was partially to destroy evidence and contain the potential damage, before handing the site over to civilian authorities.
Use of lethal force
Despite being a peace-keeping organization, UNATCO seems overly reliant on lethal force and violence; shown through several e-mails, conversations and perhaps most clearly by the attitude of numerous troopers - and especially agents Navarre and Hermann.
Only Sam Carter seems to see value in using non-lethal force; he will reward JC if he doesn't enter Castle Clinton through the front and kill everyone. Also, many of UNATCO's footmen dislikes JC if he decides to do things non lethally stating how the opposition will use what limited legal rights they have to sue the UNATCO for their disregard for human rights.
In the game, the player meets two mechanically augmented agents (often referred to as mechs): Gunther Hermann and Anna Navarre. It is shown that they work together and remain close friends. Being stronger and more able than UNATCO Troopers, their role is usually to go into terrorist situations alone and complete objectives, while Troopers usually follow behind and exterminate all enemies. Upon the player's arrival at UNATCO, both agents are very bitter as they feel that they have been made obsolete by the presence of nano-augmented agents, JC Denton and Paul Denton.
The game centers around JC Denton, a nano-augmented agent. The notion is that JC Denton's tissues are augmented with nanobots that increase certain attributes of his performance related to intelligence, stealth, speed, strength or combat abilities. JC Denton's brother, Paul Denton, is also a nano-augmented agent. The advantage of nano-augmentation over mechanical augmentation is that a nano-augmented agent is visually indistinguishable from any member of the public, unlike a mechanically augmented agent. The 'nano-augs', as they are typically referred to, tend to be more physically able than their mechanical counterparts, who often encounter trouble with their augmentations, and are also able to upgrade their systems with augmentation canisters, encountered through the game. Nano-Augmented agents are the new generation of antiterrorist agents.
- When the game was released in 2000 Ion Storm created a website (www.unatco.org) for the fictional organization to promote the game. After the September 11th terrorist attacks, however, the organization might have been a little too believable; Ion Storm pulled the website shortly after the attacks.
- The motto of UNATCO is from the Sententiae of Publilius Syrus: "Nihil aliud scit necessitas quam vincere," loosely, "Necessity knows nothing else but victory."
- Comment: "These troopers, two men, are in the captured NSF headquarters in New York. They're chatting about the secret payments Walton Simons sends to UNATCO."
TrooperTalking1: "... but what's it for?"
TrooperTalking2: "That's a dumb question."
TrooperTalking1: "No, really. What does UNATCO need with that kind of money?"
TrooperTalking2: "Just look around. Think UNATCO'd be handing out assault guns if funding was left to the UN?"
TrooperTalking2: "The uniforms... If it wasn't for Simons, we'd still be wearing those little white helmets."
Comment: "A breathy laugh."
TrooperTalking2: "He's what they call a philanthropist."
Comment: "This is an aside; they're talking about classified material the rebels stole but which they are deleting.""
TrooperTalking1: "Axe this file?"
TrooperTalking2: "Yeah, all of it. The whole directory."
TrooperTalking1: "What I want to know is what he gets in return."
TrooperTalking2: "Don't you know what a philanthropist is?"
Comment: "He should mispronounce Nietzche as "Neechee.""
TrooperTalking1: "Yeah, like Nietzche."
TrooperTalking2: "No, a philanthropist. Giving to charity."
TrooperTalking2: "That's why he volunteered for FEMA, to help out after hurricanes and that kind of thing."
TrooperTalking2: "Some people are just good, you know? Good to the bone."
- UNATCO trooper: "Turns out your brother was stealing balance sheets from UNATCO's accounting department. "
- UNACO Trooper: "Damage control. The NSF got their hands on some pretty sensitive material. "
- UNATCO trooper: "The civilian authorities will take over tomorrow."