XOF

XOF was a military group that existed some time around the mid 1970s and early '80s. During this time, they were led by a heavily scarred man known by the codename of "Skull Face." The group's logo utilized an inverted image of a fox that was used by the (then defunct) FOX Unit.

History
XOF was involved in the imprisonment of the former child soldier Chico at Camp Omega, prompting a rescue effort from Big Boss of the Militaires Sans Frontières. They had also detained ex-Cipher agent Paz Ortega Andrade,  after a Belizean fishing boat recovered her from sea, having held her for interrogation on behalf of her former employers.

After XOF's commander, Skull Face, visited Chico at Camp Omega, and told him to, "Give my regards to your Boss, when you get home," anticipating the arrival of Big Boss at Camp Omega, the group commenced their "Trojan Horse" operation; an assault on the MSF's Mother Base, under the guise of a UN nuclear inspection, though Big Boss, Kazuhira Miller, Huey, and one MSF soldier were able to escape.

While undergoing their activities, XOF claimed to be a CIA-based unit. However, one of the Pentagon's moles, an undercover agent uncovered and likewise relayed to Big Boss that XOF was not actually aligned with the CIA at all.

The Marines stationed at the base had no idea who XOF were but did have some suspicions about them.

Equipment and functions
During the events of the mid 1970s and early '80s, regular XOF soldiers wore Olive drab uniforms and combat boots, a chest harness, a balaclava, a ballistic helmet with a designation number painted on and eye protection goggles. Some also wore headsets for communication, and all wore black brassards on the left arm with XOF logo velcroed on for easy disposing. These soldiers were armed with M1911 series pistols, Ruger MP9s modified with Skorpion vz. 61 folding stocks, SAR-80s and SIG SG 550s, and had access to aircraft and vehicles, such as modified Blackhawks with retractable gears and refueling booms, APCs, and jeeps.

Behind the scenes
XOF first appeared in the PAX Prime 2012 demo for Metal Gear Solid V: Ground Zeroes (at the time simply titled as Metal Gear Solid: Ground Zeroes). In both the VGA 2012 trailer for The Phantom Pain, and the GDC 2013 trailer for Metal Gear Solid V: The Phantom Pain, there are soldiers shown attacking a hospital that utilize similar uniforms and equipment to XOF, although it is currently unclear if they are the same group.

In the demo shown at the Kojima Productions Los Angeles studio live opening, the XOF members, when disposing of their XOF badges, also released a FOX badge, with the player later finding it after interrogating a soldier about it. It was later confirmed that the XOF patches were indeed collectible in-game, and that collecting them all will unlock the extra op mission ("Deja Vu" for the PS3/PS4 releases, and "Jamais Vu" for the Xbox 360/Xbox One releases).

Notes and references
XOF