The United Nations, abbreviated UN, is the governmental body of Earth. It was founded in 1945 after World War II as an international organization facilitating cooperation in, among other areas, international law. It is led by the elected Secretary-General, who at the time the Expanse takes place is Esteban Sorrento-Gillis.
The UN is seated on Earth, but also has a presence on Luna, in the New Hague facilities in Lovell City. It controls the United Nations Navy (UNN) and the United Nations Marine Corps (UNMC).