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What is Terrorism?

Terrorism is the use of force or violence against people or property in violation of the criminal laws of the U.S. for purposes of intimidation, coercion, or ransom.

Terrorism Facts

  • Terrorists often use threats to create fear among the public, to convince citizens that their government is unable to protect them, and to get immediate publicity for their causes.
  • Acts of terrorism include: threats of terrorism; assassinations; kidnappings; hijackings; bomb scares and bombings; cyber attacks (computer-based); and the use of chemical, biological, radiological, and nuclear weapons.
  • High-risk targets for acts of terrorism include military and civilian government facilities, international airports, large cities, and high profile landmarks. Terrorists might also target large public gatherings, water and food supplies, utilities, and corporate centers.

Chemical Threats

  • Chemical agents are poisonous vapors, aerosols, liquids, and solids that have a toxic effect on people, animals, or plants.
  • They can be released by bombs or sprayed from aircraft, boats, and vehicles. They can be used as a liquid to create a hazard to people and the environment.
  • Some chemical agents may be odorless and tasteless.
  • They can have an immediate effect (a few seconds to a few minutes) or a delayed effect (two to 48 hours).

Biological Threats

  • Biological agents are organisms or toxins that can kill or incapacitate people, livestock, and crops.
  • The three basic groups of biological agents that would likely be used as weapons are bacteria, viruses, and toxins.
  • Biological agents can be dispersed by spraying them into the air, by infecting animals that carry the disease to humans, and by contaminating food and water.

Radiological Dispersion Device (RDD)

  • Terrorist use of an RDD (often called dirty nuke or dirty bomb) is considered far more likely than use of a nuclear explosive device. An RDD combines a conventional explosive device (such as a bomb) with radioactive material. It is designed to scatter dangerous and sub-lethal amounts of radioactive material over a general area.
  • Depending on the speed at which the area of the RDD detonation was evacuated or how successful people were at safely sheltering-in-place, the number of deaths and injuries from an RDD might not be substantially greater than from a conventional bomb explosion.

Nuclear Blasts - A nuclear blast is an explosion with intense light and heat, a damaging pressure wave, and widespread radioactive material that can contaminate the air, water, and ground surfaces for miles around. A nuclear device can range from a weapon carried by an intercontinental missile launched by a hostile nation or terrorist organization, to a small portable nuclear device transported by an individual.

Actions to Consider


  • Learn about the nature of terrorism.
  • Be aware of your surroundings.
  • Take precautions when traveling.
  • Leave an area if you feel uncomfortable or if something does not seem right.
  • Assemble an emergency supply kit.
  • Create an evacuation plan for your family and have a backup route in mind.
  • Determine an out-of-town relative that all family members can use as a contact if separated.


  • Take cover immediately.
  • Stay low to the floor or ground.
  • Listen to local radio or television stations for updates.
  • Evacuate immediately if directed to do so.


  • Stay away from the incident area; there may be danger of secondary devices.
  • Check for injured and trapped people if already near the event area and provide first aid and CPR if trained to do so.
  • Notify your friends and/or family of your condition.
  • Use phone services sparingly.
  • Listen to local radio or television stations for the latest information.
  • Check the foundation, chimney, and land surrounding your home for damage. Be especially careful of downed power lines and ruptured gas lines.
  • Report property damage to your insurance agent immediately.

The National Terrorism Advisory System
The National Terrorism Advisory System (NTAS) replaces the color-coded Homeland Security Advisory System. This new system will more effectively communicate information about terrorist threats by providing timely, detailed information to the public, government agencies, first responders, airports and other transportation hubs, and the private sector. It recognizes that Americans all share responsibility for the nation's security, and should always be aware of the heightened risk of terrorist attack in the U.S. and what they should do.

After reviewing the available information, the Secretary of Homeland Security will decide, in coordination with other Federal entities, whether an NTAS Alert should be issued. NTAS Alerts will only be issued when credible information is available. These alerts will include a clear statement that there is an imminent threat or elevated threat. Using available information, the alerts will provide a concise summary of the potential threat, information about actions being taken to ensure public safety, and recommended steps that individuals, communities, businesses and governments can take to help prevent, mitigate or respond to the threat. The NTAS Alerts will be based on the nature of the threat: in some cases, alerts will be sent directly to law enforcement or affected areas of the private sector, while in others, alerts will be issued more broadly to the American people through both official and media channels.

NTAS Alerts contain a sunset provision indicating a specific date when the alert expires, there will not be a constant NTAS Alert or blanket warning that there is an overarching threat. If threat information changes for an alert, the Secretary of Homeland Security may announce an updated NTAS Alert. All changes, including the announcement that cancels an NTAS Alert, will be distributed the same way as the original alert.

Imminent Threat Alert - Warns of a credible, specific, and impending terrorist threat against the U.S. 

Elevated Threat Alert - Warns of a credible terrorist threat against the U.S.

Sunset Provision - An individual threat alert is issued for a specific time period and then automatically expires. It may be extended if new information becomes available or the threat evolves.

Terrorism Information
Terrorism information and intelligence is based on the collection, analysis and reporting of a range of sources and methods. While intelligence may indicate that a threat is credible, specific details may still not be known. As such, Americans should continue to stay informed and vigilant throughout the duration of an NTAS Alert.

How can you help? Each alert provides information to the public about the threat, including, if available, the geographic region, mode of transportation, or critical infrastructure potentially affected by the threat; protective actions being taken by authorities, and steps that individuals and communities can take to protect themselves and their families, and help prevent, mitigate or respond to the threat. During an alert, stay vigilant and if you see something suspicious report it to local law enforcement or call 911 (or equivalent).

Installation Notification and Warning Systems
Installation Notification and Warning Systems (INWS) may be activated independently or in conjunction with the NTAS Alerts. INWS include: Giant Voice (outdoor speakers), indoor speaker systems, telephone alert systems, and desktop alerts to name a few. Check with your installation on the method(s) typically used to warn and notify people of potential events.

Force Protection
Conditions Force Protection Conditions (FPCONs) initiate various tasks that increasingly restrict movement and require more stringent security and identification checks throughout the installation and of individuals. FPCON-"Normal" is the least stringent within the system and is used day-to-day when no threats exist and escalates through FPCON Levels; Alpha, Bravo, Charlie and Delta, with Delta being the highest FPCON Level where the base is virtually locked down with no movement other than Security Forces and emergency responders allowed. FPCONs are normally broadcast through various mass notification systems and posted at entry control points. NTAS Alerts will be issued through state, local and tribal partners, the news media and directly to the public via the following channels:



Social Media
The public can also expect to see alerts in places, both public and private, such as transit hubs, airports and government buildings.

To find out more about the NTAS, visit the official DHS NTAS webpage.

Did you Know...

The degree of exposure for people inside a closed building when a biological or chemical plume passes outside is reduced by a factor of two or more for typical American homes and by a factor of as much as 10 or more for hermetically sealed office buildings, depending on the quality of the air filters in the heating, ventilation, and air conditioning system.

Contact your local or Installation's Office of Emergency Management for more information.