A man walks past candles lit to mark the second anniversary commemorations of the Westgate shopping mall attack by militants from Somalia's Al-Qaeda-affiliated Shebab on September 21, 2015 in Nairobi.The attack began on September 21, 2013, when four gunmen entered the mall, spraying shoppers and staff with machine gun fire and tossing grenades into crowds of Saturday shoppers and diners. The attack left 67 dead. AFP PHOTO / SIMON MAINA        (Photo credit should read SIMON MAINA/AFP/Getty Images)