GMP

GMP (short for Gross Military Product) was a currency used by the Militaires Sans Frontières and Diamond Dogs private military companies between the 1970s and 1980s.

GMP was primarily used by Big Boss' mercenary companies as a means of pursuing research and development for military equipment. It was supplied by the Combat Unit, with the more skilled combatants providing more GMP.

During the 1980s, GMP was used by the Diamond Dogs to operate the Fulton Recovery system, with both target recovery and cargo drops costing GMP.

Behind the scenes
GMP was introduced to the Metal Gear series in Metal Gear Solid: Peace Walker as an in-game currency. It is used exclusively by MSF, assisting in Mother Base's establishment as an offshore sovereign state. In Peace Walker, players can gain more GMP by adding more soldiers to Mother Base's Combat Unit. The more combat experience these soldiers receive (such as Extra Ops or Outer Ops), the higher their stats become, and the more GMP is generated.

While absent from Metal Gear Solid V: Ground Zeroes (as there is no Mother Base or Fulton Recovery), GMP returns in Metal Gear Solid V: The Phantom Pain for similar purposes as Peace Walker.