Mozambique: Why IS is so hard to defeat in Mozambique

The recent bloodthirsty raid by jihadist militants from the Islamic State group (IS) in northern Mozambique has shocked the world.

Hundreds of well-armed fighters were able to overrun a town close to Africa's largest gas project. They massacred dozens of people, locals and expatriates, leaving decapitated bodies strewn around the streets.

So how was this able to happen, why can the Mozambican government not control this insurgency and what will it take to defeat it?