France, Dec. 29 -- Al-Shabaab ("The Youth") rose to prominence in Somalia in the early 2000s andaims to establish a "Greater Somalia", joining ethnic Somalis across East Africa under strict Islamic rule.

It has allegedly become one of al-Qaeda's strongest and most successful affiliates.

A joint United Nations and African Union peacekeeping force known as the African Union Transitional Mission to Somalia (ATMIS), along with the United States and several East African nations, have been actively trying to combat the movement, but it has proven resilient againstnumerous counterinsurgency campaigns.

RFI: Why have Shabaab militants been able to regain the ground they lost over the past three years?

Matt Bryden: Three years ago, the offensiv...