For years, private armies have provided services to governments around the world. They are often secretive and operate in the shadows.
Blackwater - now known as Academi - is one of the most well-known private armies. It has provided troops and other services to the US government in different conflicts, including the Iraq war.
But it is not always clear how these private armies are formed, where they operate, or even what their missions consist of.
Eeben Barlow is chairman of 'Specialised Tasks, Training, Equipment and Protection International' - a private army that - according to Barlow - has operated throughout Africa and beyond. He was also behind another similar company that shut down in 1998 - called Executive Outcomes.
And while many argue private armies are mercenaries doing the jobs governments do not want to do - Barlow insists his operations are legitimate and follow international law.
So who makes sure these armies are indeed following international law? How do they operate? And is there accountability?
Eeben Barlow provides an insight into the world of private military contractors as he talks to Al Jazeera about his company's role in fighting Boko Haram in Nigeria, the LRA in Uganda and other conflicts across Africa.
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