Understanding Different Types of Terrorism

Burning Car

Supoj Buranaprapapong / Getty Images

Different types of terrorism have been defined by lawmakers, security professionals, and scholars. Types differ according to what kind of attack agents an attacker uses (biological, for example) or by what they are trying to defend (as in ecoterrorism). 

Researchers in the United States began to distinguish different types of terrorism in the 1970s, following a decade in which both domestic and international groups flourished. By that point, modern groups had begun to use techniques such as hijacking, bombing, diplomatic kidnapping, and assassination to assert their demands and, for the first time, they appeared as real threats to Western democracies, in the view of politicians, lawmakers, law enforcement and researchers. They began to distinguish different types of terrorism as part of the larger effort to understand how to counter and deter it.

Here is a comprehensive list of types of terrorism, with links to more information, examples, and definitions.

State Terrorism

Many definitions of terrorism restrict it to acts by non-state actors.

But it can also be argued that states can, and have, been terrorists. State terrorists can use force or the threat of force, without declaring war, to terrorize citizens and achieve a political goal. Germany under Nazi rule has been described in this way.​

It has also been argued that states participate in international terrorism, often by proxy. The United States considers Iran the most prolific sponsor of terrorism because Iran arms groups, such as Hizballah, that help carry out its foreign policy objectives. The United States has also been called a terrorist, for example through its covert sponsorship of Nicaraguan Contras in the 1980s.


Bioterrorism refers to the intentional release of toxic biological agents to harm and terrorize civilians, in the name of a political or other cause. The U.S. Center for Disease Control has classified the viruses, bacteria, and toxins that could be used in an attack. Category A Biological Diseases are those most likely to do the most damage. They include:

  • Anthrax (Bacillus anthracis)
  • Botulism (Clostridium botulinum toxin)
  • The Plague (Yersinia pestis)
  • Smallpox (Variola major)
  • Tularemia (Francisella tularensis)
  • Hemorrhagic fever, due to Ebola Virus or Marburg Virus


Cyberterrorists use information technology to attack civilians and draw attention to their cause. This may mean that they use information technology, such as computer systems or telecommunications, as a tool to orchestrate a traditional attack. More often, cyberterrorism refers to an attack on information technology itself in a way that would radically disrupt networked services. For example, cyber terrorists could disable networked emergency systems or hack into networks housing critical financial information. There is wide disagreement over the extent of the existing threat by ​cyber terrorists.


Ecoterrorism is a recently coined term describing violence in the interests of environmentalism. In general, environmental extremists sabotage property to inflict economic damage on industries or actors they see as harming animals or the natural environment. These have included fur companies, logging companies, and animal research laboratories, for example.

Nuclear Terrorism

Nuclear terrorism refers to a number of different ways nuclear materials might be exploited as a terrorist tactic. These include attacking nuclear facilities, purchasing nuclear weapons, or building nuclear weapons or otherwise finding ways to disperse radioactive materials.


Narcoterrorism has had several meanings since its coining in 1983. It once denoted violence used by drug traffickers to influence governments or prevent government efforts to stop the drug trade. In the last several years, narcoterrorism has been used to indicate situations in which terrorist groups use drug trafficking to fund their other operations.