PLANT and ZAFT
Located at Side 2, the PLANTs (Productive Location Ally on Nexus Technology, later People Liberation Acting Nation of Technology) began as an experiment in tighter control of semi-autonomous space colonies after the establishment of the Autonomous Republic of Munzo (later Zeon). Almost entirely industrial, with no military presence and legally prohibited from producing sufficient food to maintain their populations, the PLANTs were billed as a solution to the problem of spacenoid independence, though perhaps not publicly in quite so many words.
The PLANTs quickly built a reputation as slums in space, with plummeting property values and difficult living conditions. Coordinators, often locked out of the job markets on Earth and in the Neo colonies due to prejudice, ended up emigrating to the PLANTs en masse, in turn causing a wave of racially-motivated terror attacks. (This concentration of the Coordinator population intensified more recently after the Axis Shock in 0093, due to an oft-repeated and unsubstantiated claim that one in four pilots under Char Aznable had been Coordinators.)
Once leadership of the PLANT Supreme Council shifted to the Zodiac Alliance in the mid-0080s, however, the PLANTs flourished. Starting from their impoverished conditions, they quickly made drastic improvements in every area not mandated by the terms of their incorporation, and became the nicest places to live in space, even ahead of the Orbital Ring. This in turn emboldened PLANT, which reached out to non-bloc and independent nations on Earth to purchase bulk food and colonial food pods, with the long-term goal of becoming food-independent against their legal mandate.
After considerable agitation and threats of secession from the PLANT Supreme Council, representatives from each Federation power bloc agreed to meet with PLANT officials to discuss a new food growth cap, setting Copernicus City as a neutral meeting ground. This meeting never occurred, with Chairman Siegel Clyne of PLANT delayed in Von Braun airspace as a terror attack in Copernicus killed the Federal delegation. REA and Union representatives both claimed this to be a sign that PLANT had gone rogue, and six days later, moved to eject PLANT from the Federation and open hostilities. The motion passed (albeit with the AEU abstaining), and three days later, Junius Seven was destroyed with a nuclear missile.
More than 90% of the population of the PLANTs is Coordinator or half-Coordinator (with the latter an extreme rarity), and within the PLANT militia, ZAFT, that number increases to more than 99%. The use of nuclear weapons against a civilian target in a post-Axis Shock world has given the population of the PLANTs powerful motivation to fight.
In the PLANTs, the war footing takes precedence over literally all other political concerns at the moment. Being hit with a nuclear attack has largely galvanized public opinion, with only a handful of exceptions. The split within the PLANTs' highest leadership echelons only very faintly favors diehard war-footing radicals, however, and there are several swing votes. The question of whether to prosecute a war against the Federation is settled; the question of how and to what extent is very much open.
Past that, however, the PLANTs are a relatively politically diverse population. While ZAFT holds a clear majority in the Supreme Council, ZAFT is a big-tent party built around basic independence issues, so most other topics enjoy relatively spirited debate.
A fair number of Neo Zeon partisans have taken up residence in the PLANTs, including some Coordinators but many Naturals. They enjoy a shaky solidarity with the Coordinators, but some already fear the possibility that the desire for revenge they share will be outstripped by racial animus.
ZAFT is the militia of the PLANTs, and by extension, the faction that fights on their behalf for the independence of the PLANTs from the Federation.
ZAFT occupies a space closer to a resistance movement (or terror network) than a military, despite its use of the enormous manufacturing base of the PLANTs. As a result, ZAFT does not actually use a conventional rank structure. Initial placement usually relates in some way to either ZAFT academy success or one's civilian position, with terms like 'captain' and 'commander' used mostly out of respect rather than rigid adherence to structure. ZAFT battle groups almost entirely follow the model of prior anti-Federation resistance organizations like the Anti Earth-Union Group or Karaba, with small numbers of ships acting mostly independently from one another.
That said, for ease of identification of personnel and their relative positions, ZAFT does signify rough levels of experience and authority through the use of uniforms. Most ZAFT troops wear green uniforms, while those who graduated top of their class at the academy or who have proven previous expertise wear a deep crimson uniform. White and black uniforms are reserved for battle group leaders and ship commanders, with purple reserved for non-frontline personnel with high levels of authority. Unimpeachable conduct and consistent results earn the right to wear a custom uniform color.
More recently, ZAFT's war power has been augmented by outside agitators. Officially, these are irregular forces who have joined with ZAFT's cause; the truth of the matter, however, is that they represent interests from the Jovian Federation and Crossbone Vanguard who consider the PLANTs' independence bid a stepping stone for their own ends.