It was in September of 2007 that the name Blackwater shot to the headlines ... a company operating largely in the shadows of the U.S. occupation of Iraq . Four of its so-called private contractors killed 14 Iraqi civilians. Witnesses say that at a crowded traffic stop known as Nusoor Square, Blackwater operatives opened fire unprovoked, as civilians fled.

This week, the four were sentenced. The incident is perhaps the highest profile example of what can go wrong when private military contractors get involved in wars.

Sean McFate is a former private military contractor, says the future of war could usher in a heavier reliance on companies like Blackwater. Which isn't to say that employing mercenaries can never work. The success of elections in Nigeria a few weeks ago, for example, are credited in part to the assistance of private South African security firms, keeping Boko Haram militants at bay.

Sean McFate is a Senior Fellow at the think-tank Atlantic Council and author of the book, "The Modern Mercenary". He was in our Washington studio.

This segment was produced by The Current's Sonya Buyting.