Making a killing: how private armies became a $120bn global industry --By Daniel Howden and Leonard Doyle in Washington

In Nigeria, corporate commandos exchange fire with local rebels attacking an oil platform. In Afghanistan, private bodyguards help to foil yet another assassination attempt on President Hamid Karzai. In Colombia, a contracted pilot comes under fire from guerrillas while spraying coca fields with pesticides. On the border between Iraq and Iran, privately owned Apache helicopters deliver US special forces to a covert operation.