against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof, in furtherance of political or social objectives." When terrorism strikes, communities may receive assistance from State and Federal agencies operating within the existing Integrated Emergency Management System. FEMA is the lead Federal agency for supporting State and local response to the consequences of terrorist attacks. The Louisiana Office of homeland Security and Emergency Preparedness is the lead State agency for supporting local response to the consequences of terrorist attacks.

Antiterrorism refers to defensive measures used to reduce the vulnerability of people and property to terrorist acts, while counterterrorism includes offensive measures taken to prevent, deter, and respond to terrorism. Within the emergency management arena, antiterrorism is a hazard mitigation activity and counterterrorism falls within the scope of preparedness, response and recovery.

Terrorism is often categorized as "domestic" or "international." This distinction refers not to where the terrorist act takes place but rather to the origin of the individuals or groups responsible for it. For example, the 1995 bombing of the Murrah Federal Building in Oklahoma City was an act of domestic terrorism, but the attacks of September 2001 were international in nature. For the purposes of consequence management, the origin of the perpetrator(s) is of less importance than the impacts of the attack on life and property; thus, the distinction between domestic and international terrorism is less relevant for the purposes of mitigation, preparedness, response, and recovery than understanding the capabilities of terrorist groups and how to respond to the impacts they can generate.