The United Colonial Nations (UCN) are the current ruling government of Earth and, indirectly, of its colonies. The UCN is also the founder of the ISA. Its largest, oldest, and most prestigious department is the United Colonial Army. There are indications that the UCN's capital may be in New York City, but the bulk of their forces are kept offworld where they can deploy on a moment's notice to Earth or any of its colonies.
Founded after World War III as the result of a resource shortage on Earth prior to colonisation, the UCN, through its military arm, the UCA, is known to have larger armies and more powerful weaponry than all of its ISA colonies combined. In an effort to enforce Earth's will on the colonies and prevent rebellions without stretching its own military dangerously thin, the UCN founded and funded the Interplanetary Strategic Alliance (ISA), a unified defence alliance for all existing and future colonies.
The UCN relies on all of its colonial resource support by taxing them a fraction of their resources such as food and minerals. Any attempts to resist are met with overwhelming force as resource-depleted Earth cannot afford to have its flow of vital commodities halted for any prolonged period of time, otherwise Earth's population would starve. As a result of its overwhelming power, and willingness to use it, some view the organization as tyrannical.
The UCN and the ISA's main news broadcasting station is the United Colonial Broadcast Network. The UCN maintains the largest forces and most technically advanced weapons systems available to humans and helghast.