The Katiba is a 6.5mm assault rifle of an Eastern origin. Developed in cooperation with China, it features a (lightweight) bullpup design, reliability and low recoil. The Katiba is a standard issue weapon for OPFOR armies. Three version of the Katiba exist: standard, a shorter carbine and a GL version equipped with an under-slung grenade launcher.
The Katiba series refer to a group of bullpup service rifles used by Mediterranean CSAT forces in ArmA 3.
All variants of the Katiba are based on the real-world "KH-2002 Khaybar" bullpup assault rifle designed by the Defense Industries Organization (DIO), a conglomerate of arms manufacturers based in Iran. The real KH-2002 has seen limited use within the Iranian Armed Forces and by certain non-state actor groups supported by Iran.
On the other hand, the Katiba GL variant's underbarrel launcher appears to be based on the "ML40 mk2" grenade launcher designed by Madritsch Weapon Technology, an arms company based in Austria.
Despite being clearly modelled with non-double stacked STANAG magazines that would only be able to fit 20 rounds, all variants of the Katiba are strangely capable of firing up to 30 rounds per magazine.
In addition, although stated to be chambered to fire caseless 6.5 mm ammunition all variants have an ejection port located just above the magwell in the stock.
During ArmA 3's pre-Alpha development phase, early media releases did not show either the Katiba or its sub-variants being used as the service weapon of Mediterranean CSAT forces. The TRG-21 was (presumably) used as a temporary placeholder instead until the Katiba was eventually added into the game.