Global Terrorism Database (Worldwide Incident Tracking System)
The Worldwide Incidents Tracking System (WITS) is the U.S. Government's database on acts of terrorism, and contains details about incidents of violence against civilians and non-combatants (including military personnel and assets outside of war-like settings) from publicly available information. National Counterterrorism Center (NCTC) analysts determine if an event meets the definitional criteria of 22 U.S.C. § 2656f(d)(2) as an act of terrorism. NCTC is not responsible for errors and omissions in open source reporting. The judgment of NCTC is not intended to be a legally binding determination that an event is a terrorist act for any purpose other than providing statistical information.
The NCTC discontinued WITS in April 2012. The data got folded into GTD, which can be downloaded from the National Consortium for the Study of Terrorism and Responses to Terrorism (START) website at the University of Maryland.