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)

A visitor takes a picture of a display bearing hand prints of war heroes from the War of Resistance against Japan, at Jianchuan Museum Cluster in Anren, Sichuan Province, China, May 13, 2016. Tucked away in southwestern China's Sichuan province, a private collector stands virtually alone in exhibiting relics from the 1966-1976 Cultural Revolution. Monday marks the 50th anniversary of the start of the political movement, with no official commemorations planned. Official records whitewash the details of both periods, but admit that Mao made major mistakes. (Photo by Kim Kyung-Hoon/Reuters)

Just Dance 2017 performance at Ubisoft E3 2016 – Day 2 at the Los Angeles Convention Center on Tuesday, June 14, 2016, in Los Angeles. (Photo by Dan Steinberg/Invision for Ubisoft/AP Images)

Muslims offer prayers during Jumat-ul-Vida or the last Friday of the holy fasting month of Ramadan in Allahabad, India, July 1, 2016. Muslims throughout the world are marking the month of Ramadan, the holiest month on the Islamic calendar, by fasting from dawn till dusk. (Photo by Jitendra Prakash/Reuters)

Deputy community chief of Yeneka village Douglas Oguta poses for a portrait in his home on the outskirts of the Bayelsa state capital, Yenagoa, in Nigeria's delta region October 8, 2015. Tensions are building in the swampland of the Niger Delta as an amnesty that aimed to bring stability to Nigeria's volatile southern region is due to expire at the end of the year. While the region's towns and cities are mostly calm, local residents say kidnappings and armed robberies are on the increase in the mangrove swamps, where most oil wells are located. (Photo by Akintunde Akinleye/Reuters)

The Jet Propulsion Lab team's RoboSimian robot turns on a valve at a simulated disaster-response course during day one of the Defense Advanced Research Projects Agency (DARPA) Robotics Challenge finals in Pomona, California, June 5, 2015. (Photo by David McNew/Reuters)

Devotees try to form a human pyramid to break a clay pot containing curd during celebrations to mark the Hindu festival of Janmashtami in Mumbai, India, September 6, 2015. Janmashtami, which marks the birthday of Hindu god Krishna, is being celebrated across the country today. (Photo by Danish Siddiqui/Reuters)

A female bodybuilder apples oil to another performer backstage before an amateur competition in the Israeli city of Dimona, in this April 3, 2014 file photo. (Photo by Finbarr O'Reilly/Reuters)