On the frontline: Battling al-Shabab in Somalia

Kenya's role in supporting a UN-backed government in neighbouring Somalia - a traditional al-Shabab stronghold - has made it a target for the group for many years.

The movement still rules vast areas of southern Somalia, where it controls trade and can raise finances for operations - such as Saturday's attack on the Nairobi shopping mall, Westgate.

Mark Doyle joined a group of African Union peacekeepers as they travelled into an area controlled by al-Shabab, just outside Somalia's second city, Kismayo.