Set in 2014, five years after the "Big Shell Incident" , Metal Gear Solid 4 portrays a world where private military companies (PMCs) have effectively replaced the world's standing armies, fighting proxy wars for business purposes. Nanotechnology has become prominent, both to enhance the capabilities and enforce the loyalty of mercenaries. The nanomachine system that PMCs use is called "Sons of the Patriots" or "SOP." The five largest of these PMCs are owned by a single mother company named Outer Heaven, operated by Liquid Ocelot. Amassing an army whose manpower rivals that of the United States, Liquid prepares to launch an armed insurrection by taking control of SOP. A rapidly aging and disillusioned Solid Snake (now known as Old Snake) is deployed into the Middle East by Roy Campbell to terminate Liquid. Guns of the Patriots takes place in five locations: the Middle East, South America, Eastern Europe, Shadow Moses Island, and last titular Metal Gear in the series - Outer Haven, a gigantic nuclear sea vessel.
