Why do Islamist Militants Gain Ground in Some Countries and Not Others?

After the attack claimed by Boko Haram in Nigeria and another blamed on al-Shabab in Kenya in which dozens were killed, we ask why does Islamic militancy get established in some countries in the Muslim world and not others? Are religious, political, economic or social reasons the main factors behind support for Islamic militant groups?

Photo: Al-Shabab militants carry out training drills near Mogadishu in Somalia two years ago. Picture: Associated Press.