During his journey, Snake becomes involved in the Soviet-Afghan and the Angolan Civil Wars and he recruits Quiet, who no longer speaks and has gained superhuman abilities; scientist Dr. Huey Emmerich; and Code Talker, a Navajo expert on parasites forced to work for Cipher. Snake also ends up capturing Eli, a British child believed to be a clone of Snake, who leads a band of child soldiers is brought to the base after an operation. Though there is speculation into whether or not he is Big Boss' son, a DNA test confirms that Venom Snake and Eli are not genetically related. Snake learns that Cipher's leader Major Zero was usurped and XOF, a rogue faction of Cipher, was responsible for destroying MSF. XOF's leader Skull Face considers Cipher's plan to unite the world for peace as the same as making it culturally American, obliterating other cultures. To avoid this, he intends to release a unique parasite that kills anyone who speaks English. A modified parasite was used to give Quiet and Skull Face's elite soldiers, the Skulls, their unusual abilities. After releasing the English strain parasite, Skull Face plans to make nuclear weapons available to as many groups as he can, believing that nuclear deterrence will stop the weapons actually being used, attaining world peace while still protecting the integrity of each culture. However, he will secretly retain remote control of the weapons. Skull Face intends to use the threat of the latest Metal Gear system, known as ST-84 "Sahelanthropus", to make nuclear weapons desirable again, but as he cannot get it to function, he is dependent on the Third Child's psychic abilities to manipulate it. During a test, the Third Child turns against Skull Face, having Sahelanthropus seriously wound him and crush the Man on Fire. Although Snake defeats the Metal Gear, he is only able to recover one of Skull Face's three parasite vials; one is missing and the other is taken by the Third Child and given to Eli. Skull Face is left to die by Snake and Miller but Huey executes him. The Diamond Dogs return to their base with Sahelanthropus. Following their return, Eli, the Third Child, and the child soldiers steal Sahelanthropus and flee the base. It transpires that the Third Child was not consciously working for Skull Face, but his psychic powers enthralled him to the will of the most vengeful person nearby, meaning Sahelanthropus' attack was instigated by Eli. An epidemic of parasites occurs on base forcing Snake to personally kill many of his own men to contain it.