Osama bin Laden's Legacy: 13 Years of Terrorist Attacks

Baghdad's U.N. Headquarters and Other Iraq Attacks
The attacks of Sept. 11 sent the U.S. into Iraq; the invasion resulted in the formation of al-Qaeda in Iraq (AQI). Though the Sunni insurgent group was not intricately tied to the larger al-Qaeda organization, it was the biggest foe in Iraq for several years, orchestrating countless suicide bombings (including the above one, which resulted in the 2003 death of U.N. Special Representative in Iraq Sergio Vieira de Mello) until a 2010 offensive killed many of its leaders.

• Inside Osama bin Laden's Pakistan Hideaway