terrorism, the calculated use of violence to create a general climate of fear in a population and thereby to bring about a particular political objective. Terrorism has been practiced by political organizations with both rightist and leftist objectives, by nationalistic and religious groups, by revolutionaries, and even by state institutions such as armies, intelligence services, and police.

Definitions of terrorism

Definitions of terrorism are usually complex and controversial, and, because of the inherent ferocity and violence of terrorism, the term in its popular usage has developed an intense stigma. It was first coined in the 1790s to refer to the terror used during the French Revolution by the revolutionaries against their opponents. The Jacobin party of Maximilien Robespierre carried out a Reign of Terror involving mass executions by the guillotine. Although terrorism in this usage implies an act of violence by a state against its domestic enemies, since the 20th century the term has been applied most frequently to violence aimed, either directly or indirectly, at governments in an effort to influence policy or topple an existing regime.

Terrorism is not legally defined in all jurisdictions; the statutes that do exist, however, generally share some common elements. Terrorism involves the use or threat of violence and seeks to create fear, not just within the direct victims but among a wide audience. The degree to which it relies on fear distinguishes terrorism from both conventional and guerrilla warfare. Although conventional military forces invariably engage in psychological warfare against the enemy, their principal means of victory is strength of arms. Similarly, guerrilla forces, which often rely on acts of terror and other forms of propaganda, aim at military victory and occasionally succeed (e.g., the Viet Cong in Vietnam and the Khmer Rouge in Cambodia). Terrorism proper is thus the calculated use of violence to generate fear, and thereby to achieve political goals, when direct military victory is not possible. This has led some social scientists to refer to guerrilla warfare as the “weapon of the weak” and terrorism as the “weapon of the weakest.”

In order to attract and maintain the publicity necessary to generate widespread fear, terrorists must engage in increasingly dramatic, violent, and high-profile attacks. These have included hijackings, hostage takings, kidnappings, mass shootings, car bombings, and, frequently, suicide bombings. Although apparently random, the victims and locations of terrorist attacks often are carefully selected for their shock value. Schools, shopping centres, bus and train stations, and restaurants and nightclubs have been targeted both because they attract large crowds and because they are places with which members of the civilian population are familiar and in which they feel at ease. The goal of terrorism generally is to destroy the public’s sense of security in the places most familiar to them. Major targets sometimes also include buildings or other locations that are important economic or political symbols, such as embassies or military installations. The hope of the terrorist is that the sense of terror these acts engender will induce the population to pressure political leaders toward a specific political end.

Some definitions treat all acts of terrorism, regardless of their political motivations, as simple criminal activity. For example, the U.S. Federal Bureau of Investigation (FBI) defines both international and domestic terrorism as involving “violent, criminal acts.” The element of criminality, however, is problematic, because it does not distinguish among different political and legal systems and thus cannot account for cases in which violent attacks against a government may be legitimate. A frequently mentioned example is the African National Congress (ANC) of South Africa, which committed violent actions against that country’s apartheid government but commanded broad sympathy throughout the world. Another example is the Resistance movement against the Nazi occupation of France during World War II.

Since the 20th century, ideology and political opportunism have led a number of countries to engage in international terrorism, often under the guise of supporting movements of national liberation. (Hence, it became a common saying that “One man’s terrorist is another man’s freedom fighter.”) The distinction between terrorism and other forms of political violence became blurred—particularly as many guerrilla groups often employed terrorist tactics—and issues of jurisdiction and legality were similarly obscured.

These problems have led some social scientists to adopt a definition of terrorism based not on criminality but on the fact that the victims of terrorist violence are most often innocent civilians. Even this definition is flexible, however, and on occasion it has been expanded to include various other factors, such as that terrorist acts are clandestine or surreptitious and that terrorist acts are intended to create an overwhelming sense of fear.

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In the late 20th century, the term ecoterrorism was used to describe acts of environmental destruction committed in order to further a political goal or as an act of war, such as the burning of Kuwaiti oil wells by the Iraqi army during the Persian Gulf War. The term also was applied to certain environmentally benign though criminal acts, such as the spiking of lumber trees, intended to disrupt or prevent activities allegedly harmful to the environment.

Since the early 21st the term stochastic terrorism has been used to designate the repeated use of hate speech or other vilifying, dehumanizing rhetoric by a political leader or other public figure that inspires one or more of the figure’s supporters to commit hate crimes or other acts of violence against a targeted person, group, or community. Because stochastic terrorists do not supply their followers with any detailed plan of attack, the particular time and place of the eventual violence are unpredictable.