In the 1970s, Big Boss formed the Soldiers Without Borders aka MSF, giving birth to the first Private Military Corporation. It was neither a mercenary force or foreign legion - it was a lucrative business that would boom 40 years later.
The end of the Cold War era meant large-scale decommissioning of military forces which produced a pool of 7 million unemployed soldiers and a surplus of weapons along with it. With multinational corporations expanding to unstable areas of the world, these soldiers were tapped for protection services, paving the way for a War Economy, just as The Patriots had wanted.
As these soldiers were organized into private military corporations (PMCs), "surrogate wars" erupted all over the world and PMCs began to rake in fortunes. Governments began to rely on PMC's to fight their wars, leading to weakened national militaries and a booming war economy. By 2014, five of the largest PMCs fell under a single mother-company named Outer Heaven led by CEO Liquid Ocelot.
The proliferation of the Sons of the Patriots System, a network of performance-enhancing nanomachines injected into soldiers, presented a singular weakness: one man could theoretically control every single soldier connected to the system. And with a fighting force that rivaled even that of the U.S. military, Liquid Ocelot launched an insurrection against The Patriots in a bid to do just that.
Now with orders from Roy Campbell and the U.N., Solid Snake, suffering from accelerated aging, is sent to the Middle East to assassinate Liquid Ocelot and prevent the coming of Outer Haven.