At the start of Deus Ex, NSF is the primary antagonist, portrayed as a notorious terrorist group that JC believes should be eradicated. This notion continues up to LaGuardia. When JC learns of Paul's involvement with the organization, and finally meets and talks to Juan Lebedev, the NSF leader, he begins to suspect that UNATCO may be the true villain, not the NSF.
When JC is ordered by Paul to go to NSF HQ to send the distress signal, he also finds, based on Paul's words, evidence of the covert financial transactions between UNATCO officials and anonymous parties, as well as UNATCO's role in the Statue bombings. When JC sends the distress signal, Walton Simons orders the UNATCO troops to kill him. Whether JC wants to or not, he is now allied with the NSF. Eventually, JC is captured and transported to MJ12's complex beneath UNATCO HQ. This confirms UNATCO's involvement in the MJ12 conspiracy, making UNATCO officially the foe, and the NSF officially the friend.
Building on the foundations laid by the 2027 New Sons of Freedom and the 2031 Northwest Secessionist Forces and the Northwest War, the National Secessionist Forces are the third organization to carry the NSF abbreviation, formed in 2042. In the wake of draconian gun control legislation in the form of the Sporting Weapons Act, the third NSF appeared again as the National Secessionist Forces. The new NSF was composed of individuals who refused to give up their rifles, grenades, land mines, and other "collectibles" prohibited by the Act. Led by General Leon Woods, the goal of the NSF was to liberate the states of Washington, Montana, Oregon, and Northern California, and secede from the United States. Originally operating in the western United States, the NSF steadily spread across the American mainland, gaining footholds and establishing a large support base in major eastern urban centers such as New York City. While the United Nations and the US government classified the NSF as a terrorist group, many people saw the NSF as liberators from an increasingly authoritarian US federal government.
Leon Woods was killed at his infamous last stand in 2045, but the NSF continued on gaining more and more strength, as well as support from Silhouette (the resistance movement against the French government), the Luminous Path Triad, and X-51 (a group of former Area 51 scientists). Dissident computer scientists and programmers, said to be based in Seattle and San Francisco, aided the NSF in setting up a highly encrypted communication network; eroding the edge that MJ12 and UNATCO had due to their control over the Aquinas network and ECHELON. At this point, the United Nations declared war on the NSF.
In the year when Deus Ex takes place (2052), the NSF discovers that the United Nations and the US government are deliberately restricting poor people from accessing Ambrosia (the vaccine for the disease known as the Gray Death) in order to control the population, and are under the control of a secret organization called Majestic 12 that is intent on gaining absolute control over everything in the world. To give the lower class the same chance to survive as the upper class and employees of the US government, they steal Ambrosia vaccines and send them to Luminous Path Triad scientist Tracer Tong to be synthesized, making the NSF popular with the lower classes. The state of Texas, which unsuccessfully tried to secede in 2032, is described in an e-mail as being in a state of constant warfare between the NSF, UNATCO and the US military.
In an attempt to reduce support for the NSF, UNATCO framed the NSF and their allies for many terrorist acts, including the bombings of the Statue of Liberty, as well as smuggling illegal drugs and immigrants (although the Luminous Path Triad, being a mafia group, is actually involved in such smuggling activities). When the NSF started running out of troops during their assault in New York City, however, they began to desperately take hostages in order to stall for time and delay UNATCO, despite a policy discouraging hostage-taking.
After the events of Deus Ex, most of the organization seems to be crippled but not destroyed. This is partly due to the actions of JC Denton, whose short tenure with UNATCO saw the capture of several important bases—including the NSF New York headquarters in Hell's Kitchen; capture or death of several commanders, including a prominent NSF leader and financial backer, Juan Ivanovich Lebedev, and the failure of a critical operation in New York City.
During the remaining course of the game, the organization remains largely intact—though with a reduced strength in the East Coast. This is probably due to the sending of the NSF distress signal by JC which allowed other NSF bases and resistance groups in Europe to take necessary counter measures. Several prominent members from the New York Section remain at large, probably waiting to reform the organization in New York; indeed, this is evidenced by the fleeing of NSF commanders Decker Parkes, Erin Todd and Wayne Young to Europe. During the game, an NSF brigade are conducting operations in Paris under the command of Chad Dumier, leader of Silhouette and the Illuminatus Morgan Everett. Morgan Everett, in conversation with JC, mentions their still-operational HQ as being a few hundred miles north of the X-51 base at Vandenberg. Near the Champs-Élysées in Paris, JC Denton overhears a man asking his wife to come with him to America, as he has been contracted to work with the NSF.
NSF terrorists are the first enemy JC Denton faces in the game. Alex Jacobson cautions JC that the NSF are "everywhere". During their first encounters they are armed with 10mm pistols, but as JC advances through New York, they become armed with better weapons, such as sawed-off shotguns and assault rifles. Three even have flamethrowers; one is under Castle Clinton, while the other is in Battery Park's subway station, the third in the Helicopter Station. They use LAMs as grenades, but very few are equipped with one. Additionally, some of them employ the use of Dobermans.
NSF terrorists are noticeably somewhat weaker than other grunt-type enemies, with only 75 health instead of 100 health, as well as worse aim and reflexes, as they are not professionals.
NSF terrorists disappear after clearing the LaGuardia Airport, except for two in the Majestic 12 complex beneath UNATCO Headquarters. These two terrorists were imprisoned; one of them (Miguel), depending on JC's actions, survives or even manage to escape. The other is found dead in his cell, with a medkit.
Despite the add-on eyewear on the ski masks, their models have eyes.
The NSF headquarters is a large, warehouse-style building in New York. To access this building, JC must go through a previously inaccessible tunnel in the second Hell's Kitchen level. The building is well-armed, with lasers, tripwires, security cameras and turrets. There are also protected rooms with arrays of mainframe computers, and atop the building is a series of satellites, which JC uses to send the distress signal to other NSF cells and Silhouette to warn them of UNATCO/MJ12's search-and-destroy operations. When JC manages to get to this building, it is overrun by UNATCO troops.
The NSF, until JC intervenes, also has control of the Warehouse District behind the Osgood and Sons Warehouse in Hell's Kitchen. This control centralizes around a single warehouse with an electrical generator used to power the EMP field around their stolen Ambrosia supplies (until JC destroys it, but not before the supplies are moved to LaGuardia).
Additionally, the NSF sets up shop at Juan Lebedev's private terminal at LaGuardia Airport. When JC arrives at the airfield, it is completely NSF-controlled. Stationed in the airfield is Lebedev's 747, where he and Paul Denton plan to carry the Ambrosia to Hong Kong, but when JC interrogates Lebedev, UNATCO recovers the Ambrosia and kills/captures all the NSF troops in the airfield (Paul manages to escape).
The NSF also sets up ad-hoc bases at the top level of the Statue of Liberty, Castle Clinton and the abandoned Brooklyn subway system (where the Mole People live). Two out of these three are taken over by UNATCO.
Stephanie Maxwell was pushing to have an NSF presence at Vandenberg to provide X-51 with armed protection. However, MJ12 attacked the complex before any arrangements could be made. However, before JC leaves, hears than a team of NSF soldiers will arrive there shortly.
- UNATCO bulletin terminal: Know Your Enemy -- NSF