U.S. Army Maj. Nidal Hasan is charged with a 2009 killing spree that killed 13 people at Fort Hood in Texas. Homegrown terrorism by Muslim Americans has been growing over the past decade. HO/AFP/Getty Images hide caption

itoggle caption HO/AFP/Getty Images

Smoke rose Sunday during demining operations at the gas plant in eastern Algeria that Islamist militants attacked last week. Louafi Larbi /Reuters /Landov hide caption

itoggle caption Louafi Larbi /Reuters /Landov

Algerian men look at national newspapers headlining the terrorist attack and kidnapping in Amenas at a news stand in Algiers on Thursday. Ouahab Hebbat/AP hide caption

itoggle caption Ouahab Hebbat/AP

A U.S. Predator drone flies through the night sky over Kandahar Air Field in Afghanistan. Such drones have been targeting groups such as the Haqqani network that are accused of attacking U.S. and Afghan forces. Kirsty Wigglesworth/AP hide caption

itoggle caption Kirsty Wigglesworth/AP

Pakistani Air Force personnel guard an air base northwest of Islamabad earlier today. It was attacked Thursday by militants armed with guns, rocket launchers and suicide vests. Aamir Qureshi /AFP/Getty Images hide caption

itoggle caption Aamir Qureshi /AFP/Getty Images