The Military Assault Command Operations (commonly abbreviated as MACO) was a United Earth organization that existed during the 2150s, prior to the founding of the Federation. The MACOs were at that time not associated with Starfleet. With the founding of the United Federation of Planets, MACO was disbanded.
25th century[]
In 2409 following the events of the Borg attack on Vega IX. The MACOs were reinstated and now almost all Starfleet vessels have a detachment aboard.