Outside conventional armed forces, there are international companies which sell military skills - in much the same way as a corporation might sell its services in the field of oil exploration, civil engineering, etc. Nowadays these are often referred to as PMCs (Private Military Companies). Examples include Executive Outcomes (active in Africa during the 1990s, but now closed down), the UK-based Sandline International (Papua New Guinea, Sierra Leone), and the US Military Professionals Resource Incorporated (MPRI).

Such companies consist largely of ex-armed forces staff, providing military advice, training, support and materiel to customers who include oil and mineral companies, and states who lack the military capabilities themselves to deal with rebel forces. These type of organisations dislike being labelled 'mercenaries', with all the negative connotations the word carries, but their operations fall squarely into the area that most civilians would think of as the realm of the mercenary. They are, on the whole, keen to point out that they have strict rules about who they will and will not work for, and always operate under the control of a client country's legitimate government.

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