The FBI has investigative jurisdiction over terrorist acts committed within the United States and against American citizens and facilities overseas. Today it is the Bureau's overriding mission to prevent acts of terrorism before they happen. The FBI's Counterterrorism Division collects, analyzes, and shares critical information and intelligence with the proper authorities to combat terrorism on three fronts: 1) international terrorism operations both within the United States and in support of extraterritorial investigations; 2) domestic terrorism operations; and 3) counterterrorism relating to both international and domestic terrorism.

As an important component to this mission, the FBI investigates matters involving the use or threats to use weapons of mass destruction including biological, chemical, and nuclear threats. The FBI is aggressively pursuing countermeasures and readiness programs to respond to a Weapons of Mass Destruction (WMD) terrorist threat or incident.  Local, state, and federal agencies in Phoenix and Tucson that would respond to a WMD have received specialized training. Simulation exercises are conducted on an ongoing basis to ensure an appropriate level of readiness.

The FBI also plays a major role in planning and coordinating the security of special events occurring in the United States. These events routinely receive a high degree of visibility both domestically and internationally and they are potentially attractive targets for acts of terrorism which could cause significant harm to the United States' national interest or to international stability or security.

In order to adequately respond to a potential terrorist threat, the FBI and other members of the law enforcement community coordinate terrorist-related matters through established Joint Terrorism Task Forces (JTTFs). By integrating the investigative resources of federal, state, and local law enforcement agencies, these JTTFs represent an effective response to the threats posed to U.S. communities by domestic and international terrorists.  FBI Phoenix has three counterterrorism task forces to address domestic and international terrorism, two in Phoenix and one in Tucson.

Public awareness and support is important in preventing acts of domestic and international terrorism. Citizens who have information concerning potential terrorist threats are urged to immediately contact the FBI.