Abandoning their home countries, the "soldiers without borders" provided their services to all clients, regardless of nation or ideology, operating from their offshore Mother Base in the Caribbean Sea, of which the group itself is called by that name. After leaving the Patriots in , Naked Snake, a. In addition, the MSF was designed to merge the small footprint and exceptional performance of special forces groups with the full military might of a full regular army, as a means to fully break free of nation-states.
To avoid enemy intelligence services like the CIA , MSF did not initially establish a permanent base, often choosing to relocate their forces as required. Employed by the Colombian government sometime after , Snake and the MSF fought an opposing mercenary unit led by Kazuhira Miller for their last contracted job. After MSF defeated the enemy force, Snake offered Miller a place in the group, which he eventually accepted, later becoming its second-in-command.
During this time, Miller viewed MSF as a new business model for private military contractors, neither acting as typical mercenaries nor a foreign legion, and intended to help the organization expand.
The two requested that the group assist " the nation without a military " because of a mysterious security company that had recently invaded their country, presumably for the CIA. The MSF then commenced operations against the occupying force in Costa Rica, later identified as Peace Sentinel , who were attempting to develop an unmanned nuclear weapon known as Peace Walker.
During their mission, the MSF also dispatched several of its forces into other war zones for income, in order to increase its numbers and resources namely small arms, missiles and uniforms as well as to feed its personnel, in the fight against the Peace Sentinel.
