Cameroon’s far north region, on the border with Nigeria, is facing a rise in suicide bombings blamed on Boko Haram extremists. To deal with the spate of attacks, Cameroonian authorities are digging a major defence mechanism: a trench that will stretch for some 100 kilometres along the border. The aim is simple: to keep the extremists out. Our correspondents report.
A programme prepared by Patrick Lovett and Christopher Davis.