The Cardassian Defense Force, alternately referred to as the Cardassian Civil Defense Force or the CDF, was the armed service of the Cardassian Union beginning in 2387, replacing the Cardassian Guard. (STO website: The Path to 2409; ST video game: Star Trek Online)
- The service is not given a single consistent name in Star Trek Online or its tie-in materials. For example, "Standoff" refers to it as both the Cardassian Defense Force and the Civil Defense Force. However, the abbreviation CDF is consistently used.
Following the Dominion War, on stardate 63976.74 (2386) the Cardassian Union signed the Federation-Cardassian Treaty of 2386 in which they agreed to dismantle most of their military and no longer wage war. In return the Federation agreed that it would provide aid to rebuild Cardassian cities and additional military protection in the event of invasion.
The next year Starfleet sent a battle group to aid in the dismantling of the Cardassian Guard. The Union intended to replace it with a smaller self defense force to patrol their own space, and to coordinate with Starfleet for threats outside their borders. This was opposed through the end of the decade by hardliners led by Gul Madred, who led rallies in 2390 advocating a return to the "true" ways of the Union. In 2393 Madred hired Alpha Jem'Hadar under Lamat'Ukan to protect his mining operations in the Septimus system, citing attacks by raiders and his belief that the CDF could not provide sufficient security.
In 2396 an audit by Detapa Council staffers determined that at least 75 warships and an unknown number of weapons were missing. Starfleet Command spokesperson Marie Durant stated they and the CDF would be investigating. In 2402 a report from the Cardassian Intelligence Bureau to Castellan Natima Lang stated that they were likely under the possession of Madred's followers, who had taken up the mantle of the True Way terrorist organization. (STO website: Star Trek Online)