A Somali police officer arrests a suspected rebel member of the al Qaeda-affiliated al Shabaab among beach goers in Mogadishu. Al Shabaab claimed responsibility for today's pre-dawn attack on a Kenyan university campus near the Somali border. The following gallery examines who is al Shabaab. Here: Somali police officer (R) arrests a suspected rebel member (L) of the Al Qaeda-affiliated al Shabaab among beach goers at the Lido beach north of Somalia's capital Mogadishu March 23, 2012. (Photo by Feisal Omar/Reuters)

Passengers climb to board an overcrowded train at a railway station in Dhaka August 8, 2013. Millions of residents in Dhaka are travelling home from the capital city to celebrate the Muslim Eid al-Fitr holiday, which marks the end of the Muslim holy fasting month of Ramadan. (Photo by Andrew Biraj/Reuters)

Alaa, an ambulance driver, feeds cats in Masaken Hanano in Aleppo, September 24, 2014. Alaa buys about $4 of meat everyday to feed about 150 abandoned cats in Masaken Hanano, a neigbourhood in Aleppo that has been abandoned because of shelling from forces loyal to Syria's president Bashar Al-Assad on it. Alaa said that he has been feeding and taking care of the cats for over 2 months. (Photo by Hosam Katan/Reuters)

A man makes a mud oven to be used for baking bread at a workshop in Najaf, south of Baghdad, July 23, 2015. (Photo by Alaa Al-Marjani/Reuters)

A member of Iraqi rapid response forces fires a rocket launcher during a battle with Islamic State militants in the district of Yarimja in southern Mosul, Iraq, January 18, 2017. (Photo by Alaa Al-Marjani/Reuters)

Members of the Iraqi Army fire towards Islamic State militant positions at the south of Mosul, Iraq December 10, 2016. (Photo by Alaa Al-Marjani/Reuters)

Iraqi women practice at the sports club in Diwaniya, Iraq on November 10, 2018. On the blue mats of the al-Rafideen Club in the conservative city of Diwaniya, some 180 km (110 miles) south of Baghdad, some 30 female wrestlers, some still wearing headscarves, train three times a week. When a big competition comes up, they train every day. (Photo by Alaa Al-Marjani/Reuters)

Iraqi rapid response forces take a selfie picture outside a hospital damaged by clashes during a battle between Iraqi forces and Islamic State militants in the Wahda district of eastern Mosul, Iraq, January 8, 2017. (Photo by Alaa Al-Marjani/Reuters)