Somalia: Under the shadow of al-Shabab
23 September 2013 Last updated at 09:40 BST
Somalia's al-Shabab militants have said they carried out the attack on a Nairobi shopping centre in "retribution" for Kenya's efforts to help the Somali government.
Kenyan troops are part of the African Union force in Somalia.
Despite losing ground, al-Shabab remains a potent threat in the country.
Mark Doyle reports from Kismayo - once the group's main base.