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)

Chile's Javier Campillay drives past the burning car of Kazakhstan's Bauyrzhan Issabayev and Gabdulla Ashimov during the Dakar Rally 2014 Stage 2 from San Luis to San Rafael, on January 6, 2014. (Photo by Jean-Paul Pelissier/AFP Photo)

A US Army M1A2 SEP tank participates in the Strong Europe Tank Challenge 2017 at the military training area in Grafenwoehr, Germany, 12 May 2017. Six North Atlantic Treaty Organization (NATO) nations and partner nations, Austria, France, Germany, Poland, Ukraine and the USA are taking part in this competing exercise. (Photo by Christian Bruna/EPA)

Pfc. Remy Bouchard swaps a cigarette for an egg with a French Orphan near La Haye Du Puits, France on July 18, 1944, which was captured by American forces. The boy is only twelve years old. (Photo by Hugh Broderick/AP Photo)

People wearing face masks to help curb the spread of the coronavirus enjoy a social dance at a public park in Beijing, Tuesday, January 12, 2021. Lockdowns have been expanded and a major political conference postponed in a province next to Beijing that is the scene of China's most serious recent COVID-19 outbreak. (Photo by Andy Wong/AP Photo)

A Vietnamese woman collects dried incense sticks at a courtyard in Quang Phu Cau village on the outskirts of Hanoi on January 9, 2020 ahead of the upcoming Lunar New Year celebrations, referred to in Vietnam as Tet. (Photo by Manan Vatsyayana/AFP Photo)

A face mask is placed on one of the 'Three business men who brought lunch' statues on Swanston street on March 29, 2020 in Melbourne, Australia. All international arrivals into Australia from midnight on Saturday will be placed into mandatory quarantine in hotels for 14 days as the Federal Government increases restrictions to stop the spread of COVID-19. (Photo by Asanka Ratnayake/Getty Images)

A woman sits on a curb at the scene of a shooting outside of a music festival along the Las Vegas Strip, Monday, October 2, 2017, in Las Vegas. Multiple victims were being transported to hospitals after a shooting late Sunday at a music festival on the Las Vegas Strip. (Photo by John Locher/AP Photo)