Domestic Terrorism in the United States: Definition and Examples

Man prays at memorial chair before the memorial service as Oklahoma City marks the 21st anniversary of the terrorist bombing on April 19, 2016 in Oklahoma City, Oklahoma.
Oklahoma City marks 21st anniversary of terror bombing.

J Pat Carter / Getty Images

Domestic terrorism in the United States consists of acts of terrorism carried out by U.S. citizens or permanent residents targeting civilian populations within the United States. While it is recognized under U.S. federal law, domestic terrorism is not an act that can be specifically prosecuted. Instead, persons accused of having committed acts of domestic terrorism are prosecuted under other federal criminal laws, such as murder and attempted murder, kidnapping, conspiracy, and destruction of property.

Key Takeaways: Domestic Terrorism

  • Domestic terrorism or “homegrown terrorism” is any act terrorism carried out by citizens of a given country against citizens of the same country.
  • While not a specific crime, domestic terrorism in the United States can be used as justification for prosecution under federal criminal laws, such as capital murder.
  • Many acts of domestic terrorism in the United States are motivated by extremist ideologies, such as white supremacy, black separatism, and anti-government ideals.
  • Acts of terrorism in the United States motivated by foreign terrorist organizations are considered acts of “homegrown violent extremist” rather than domestic terrorism.

Terrorism vs. Domestic Terrorism

Aside from the fact that it involves violence and the threat of violence, there is no universally-accepted definition of terrorism or its many causes. Due to terrorism’s political and emotional overtones, governments have hesitated to develop an agreed-upon definition that can be used to tie terrorist acts to specific laws. In the United States, however, various government agencies have developed definitions of terrorism and domestic or “homegrown” terrorism.

In 2003, the U.S. Department of State defined terrorism as an act of “premeditated, politically motivated violence perpetrated against noncombatant targets by subnational groups or clandestine agents, usually intended to influence an audience.”

The best-recognized form of terrorism, “international terrorism” is terrorism involving citizens or the territory of more than one country.

Domestic Terrorism

Author and Central Intelligence Agency research psychologist Gary M. Jackson, Ph.D., has defined domestic terrorism or “homegrown terrorism” as acts of terrorism in which victims “within a country are targeted by a perpetrator with the same citizenship” as those victims.

The Federal Bureau of Investigation (FBI) refines Jackson’s general definition to include acts “perpetrated by individuals and/or groups inspired by or associated with primarily U.S.-based movements that espouse extremist ideologies of a political, religious, social, racial, or environmental nature.” 

Prior to the September 11, 2001 terror attacks, domestic terrorism, while common, was not specifically defined under United States law. Enacted on October 26, 2001, the USA PATRIOT Act expanded the legal definition of terrorism to include “domestic terrorism,” as opposed to international terrorism.

Under Section 802 of the PATRIOT Act, a person may be deemed to have engaged in domestic terrorism if they commit any act “dangerous to human life” that violates the criminal laws of a state or of the United States if the act appears to be intended to: 

  • intimidate or coerce a civilian population;
  • influence the policy of a government by intimidation or coercion; or
  • affect the conduct of a government by mass destruction, assassination, or kidnapping. 

In addition, the act must “occur primarily within the territorial jurisdiction of the United States.” Otherwise, the act may be treated as international terrorism.

Section 802 of the PATRIOT Act did not make domestic terrorism a new specific crime. Instead, it expanded the range of conduct the government can investigate under the umbrella definition of “terrorism” to include domestic terrorism. Persons suspected of committing acts of domestic terrorism charged and prosecuted under specific existing laws, like the murder of a federal agent or “attempting to use explosives to destroy a building in interstate commerce.”

Prevalence of Domestic Terrorism

Long before it was officially defined in 2001 by the PATRIOT Act, domestic terrorism was common in the United States.

According to the FBI, three-fourths of the 335 confirmed incidents of terrorism carried out inside the United States between 1980 and 2000 were carried out by American citizens or lawful permanent residents. The deadliest of these acts, the April 1995 Oklahoma City bombing, killed 168 people and injured more than 500.

More recently, the FBI reported the arrests of 355 suspects on charges related to domestic terrorism from 2016 to 2018. The “vast majority” of those arrested were motivated by racist and anti-government ideology, according to the FBI.

Domestic terrorists are also a growing concern among local law enforcement agencies. In 2011, Los Angeles Deputy Police Chief Michael P. Downing included “black separatists, white supremacist/sovereign citizen extremists, and animal rights terrorists,” among his agency’s top counterterrorism concerns.

Extremism and Domestic Terrorism

Since Al Qaeda’s attacks of September 11, 2001, the United States’ mainline counterterrorism policy has stressed preventing terrorism perpetrated by Islamic jihadists. However, a significant and growing number of domestic terrorist attacks have been carried out by persons motivated by U.S.-based extremist ideologies and movements. In 1999, for example, the FBI reported that “During the past 30 years, the vast majority—but not all—of the deadly terrorist attacks occurring in the United States have been perpetrated by domestic extremists.”

As reported by the Congressional Research Service (CRS) reports, neither the U.S. Department of Justice nor the FBI designated domestic terrorist organizations. However, they have openly described potential domestic terrorist “threats,” as including “individuals who commit crimes in the name of ideologies supporting animal rights, environmental rights, anarchism, white supremacy, anti-government ideals, black separatism, and beliefs about abortion,” among others. In a 2014 national survey of state and local law enforcement officers, anti-government extremist “sovereign citizens” groups and militias were “the top concern” among terrorist threats.

Clearly, a line exists between exercising one’s constitutionally protected freedom of speech and carrying out criminal acts of violent extremism. As the CRS notes, domestic terrorists often separate themselves from groups that openly and legally express ideological beliefs similar to their own. In essence, domestic terrorists are distinct from propagandists who constitutionally express opinions that might be interpreted to support their acts of violence. Thus, domestic terrorists, operating autonomously and in secret, often claim the propagandists’ legally-expressed view as justification for their violent acts. For example, domestic terrorists have used the non-violent ideologies of the Black Lives Matter organization as justification for attacks on police officers. 

Today, the FBI uses the term “homegrown violent extremist” (HVE) to separate domestic terrorists from U.S.-based terrorists motivated by the ideologies of foreign terrorist organizations, such as ISIS. According to the FBI and the Department of Homeland Security, an HVE is not a domestic terrorist.

Recent Examples of Domestic Terrorism

Since the 1995 Oklahoma City bombing made the public aware of the term, acts of domestic terrorism have killed American citizens and damaged property across the country. Some of the most recent of these acts include:

Charleston Church Shooting (2015)

On June 17, 2015, Dylann Roof, a 21-year-old, South Carolina-born white man, entered the historically black Emanuel African Methodist Episcopal Church in Charleston, South Carolina, where he shot and killed nine black worshipers. A self-avowed white supremacist, Roof admired South African racial apartheid, maintained a website where he related his negative views of black people, and expressed his hopes of starting a race war.

Orlando Nightclub Shooting (2016)

On June 12, 2016, Omar Mateen, a 29-year-old security guard, shot 49 people to death inside the Orlando, Florida, gay nightclub, Pulse. After a three-hour standoff, Mateen was killed by police. In a 911 call made shortly after the shooting, Mateen swore allegiance to the leader of the Islamic State of Iraq, Abu Bakr al-Baghdadi. The incident was the deadliest attack against LGBT people in U.S. history and was deemed a terrorist attack by the FBI.

Tree of Life Synagogue Shooting (2018)

On October 27, 2018, a mass shooting at the Tree of Life synagogue in Pittsburgh, Pennsylvania, took the lives of 11 people. The accused shooter, Robert Gregory Bowers, was a devotee of the Gab website, a site described as a “safe haven” for neo-Nazis, white supremacists, and the alt-right. Charged with 63 federal crimes, Bowers pleaded not guilty to the deadliest attack on the Jewish community in the United States.

El Paso Walmart Shooting (2019)

On August 3, 2019, Patrick Crusius, a 21-year-old white man, shot and killed 22 people inside an El Paso, Texas, Walmart store. In his manifesto posted on the now-defunct 8chan “dark” website, Crusius described a “Hispanic invasion of Texas,” stating that he was dedicated to “simply trying to defend my country from ethnic and cultural replacement.” On October 10, 2019, Crusius pleaded not guilty to federal charges of capital murder as the FBI continued to investigate the shooting as an act of domestic terrorism and a possible hate crime.

Sources and Further Reference