|The following is based on the spin off novel by Keith R. A. DeCandido and some details might contradict canon.|
The Global Defense Initiative United Peacekeepers (GDIUP) is the armed forces division of GDI.
Prior to the Third Tiberium War, GDI reorganized into a massive multinational organization to succeed the weakening United Nations and local governments. Among these changes was developing a civilian administrative bureaucracy, as well as separating the military forces into a new branch, the GDIUP. GDIUP was commanded by a Supreme Commander appointed by the Council of Directors.
Although officially separate from the political divisions, GDIUP and the bureaucracy are often considered one and the same.
Behind the Scenes
The GDI United Peacekeepers is only mentioned in the Tiberium Wars novel.