Terrorism by the Numbers

On June 15, 2021, President Joe Biden announced the United States’ first-ever National Strategy for Countering Domestic Terrorism. This new approach, directed at addressing the dangers of domestic terrorism, marked a shift away from previous U.S. counterterrorism strategy, which since the attacks of September 11, 2001, has focused on the risk of terrorist attacks from abroad. 

With so much changing, data can help explain where terrorist threats to the United States come from and whether the country is at higher risk of terrorism than other places around the world.

Since 9/11, terrorism has loomed large as a pervasive security issue. Has terrorism really reached an unprecedented level, or has sensational news coverage inflated the threat? Is terrorism a danger in some places more than others?

To start answering those questions, the first step is to determine what actually counts as a terrorist attack.

Defining terrorism is a challenge, requiring researchers to make a number of decisions when classifying incidents as terrorist attacks. 

The Global Terrorism Database, operated by START at the University of Maryland, is the largest public database on terrorist violence. It is a compilation of every terrorism incident on record since 1970 and includes information detailing the location of each attack, the group responsible, the type of weapon used, the number of casualties, and more.

START’s definition of a terrorist incident is based on three criteria; an attack must meet at least two of those to be listed in the START database:

• The violent incident is designed to meet a political, economic, religious, or social goal.
• It’s meant to coerce, intimidate, or convey another message to a broader audience.
• It targets civilians and is not an act of war.

Terrorism is, by definition, frightening. When fear drives decision-making, the resulting policies can easily respond to the wrong threats. Collecting global data on terrorist attacks and deaths allows researchers to confirm or challenge claims about the threat of terrorism, which can be inflated by politicians or media coverage. The data collected by START reveals, among other things, that the vast majority of terrorist attacks don’t make international headlines, and half of terrorist attacks claim no lives. A comprehensive look at terrorism allows policymakers to develop strategies that take into account the real nature of terrorist attacks: the groups responsible, the methods they use, the grievances that drive them, and the places they act.

What trends emerge from the data in our post-9/11 world? 

Zeroing in on the United States reveals that terrorism-related deaths have increased since 2013 after a decade of remaining relatively low. The uptick in fatal terrorist incidents and particularly lethal events—like mass shootings—have caused this spike.

Because the overall volume of terrorist attacks in the United States is low relative to other parts of the world, one attack with a significant number of casualties can have an outsize effect on the data. Although upward trends are worrying, the United States faces a relatively low threat from terrorism compared to other parts of the world.

Globally, terrorist violence went up significantly between 2002 and 2014.

This trend began to reverse itself in 2014, which was the deadliest year on record in terms of terrorism-related deaths. Since 2014, both the number of terrorist incidents and resulting deaths have actually declined—a trend not always clear from media coverage—but both remain at historically high levels. For example, terrorist attacks in 2017 were more than three times as common as they were in 2007.

Both the 2014 peak in terrorist violence and the subsequent decline are the result of a stark reality: a few particularly lethal groups operating in areas of conflict across the Middle East, Asia, and sub-Saharan Africa have driven a majority of the world’s deaths due to terrorism. 

Up to 99 percent of all terrorism-related deaths have occurred in countries embroiled in conflict or that have high levels of political terror (meaning extrajudicial killings, torture, and imprisonment without trial), such as Iraq, Somalia, and Syria. In 2018, over half of all deaths from terrorism took place in Afghanistan and Nigeria.

The Islamic State, Boko Haram, the Taliban, and al-Shabab (an al-Qaeda affiliate) were responsible for more than half—53 percent—of all terrorism-related deaths caused by known groups between 2002 and 2018.

Logically, then, the decrease in terrorist violence since 2014 is the result of the containment of the deadliest terrorist groups in the places where they are most active. The Islamic State has lost all of its territory in Iraq and Syria, and starting in 2015 Nigeria launched a military campaign against Boko Haram.

The data illustrates the correlation between conflict and terrorism, which START does not consider an act of war, but mostly happens within the context of conflict. As conflict has died down, so has terrorism: deaths from terrorism and battlefield deaths have climbed and fallen together in countries like Afghanistan, Iraq, Pakistan, and Yemen. Analyzing these two trends, it’s clear that the vast majority of terrorism is used as a tactic within an armed conflict or against repressive political regimes.

However, several Western countries—many without a recent history of conflict within their borders—have experienced an alarming trend: a surge in far-right terror attacks.

The 2020 Global Terrorism Index (GTI), using data from START’s Global Terrorism Database as well as other sources, reported that since 2014 far-right attacks have increased 250 percent to reach forty-nine incidents across North America, Oceania (Australia and New Zealand), and Western Europe, and related deaths have spiked by more than 700 percent, from eleven deaths in 2014 to eighty-nine in 2019. And although these attacks and deaths represent a small minority of terrorist incidents and casualties worldwide, they illustrate a growing threat.

Why are these attacks increasing? And what are far-right terrorists trying to accomplish? 

According to the GTI, the far right refers to a political ideology focused on one or more of the following elements: strident nationalism that is usually somehow racial or exclusivist, fascism, racism, anti-Semitism, anti-immigration sentiment, chauvinism, nativism, and xenophobia.

A multitude of factors drives the far right, including disillusionment with government and a sense of perceived victimhood. In the West, far-right terrorism has also escalated amid growing political unrest and polarization. 

According to the GTI, this ideology poses a particular threat to the United States. Half of all far-right terror incidents between 2002 and 2019 occurred in the country, as did 40 percent of all deaths, of which there were 113. 

Back in 2009, a U.S. Department of Homeland Security (DHS) report [PDF] warned that the election of the country’s first Black president, as well as the economic recession, would “present unique drivers for right-wing radicalization and recruitment.” More than a decade later, in October 2020, the DHS labeled white supremacist extremists the “most persistent and lethal threat” facing the United States.

White supremacist extremists believe in the global superiority of white people and oppose what they see as the deliberate erosion of white societies by changing demographics and immigration. And although the violent activities of white supremacists—some of whom were part of the mob at the U.S. Capitol insurrection on January 6, 2021—have recently dominated headlines, this ideology is nothing new. 

Experts trace the roots of white supremacist ideology back to the age of imperialism and the transatlantic slave trade and see its influence throughout history on laws, institutions, and events such as the development of the Jim Crow segregation system in the United States after the American Civil War and the rise of South Africa’s apartheid government in the mid-twentieth century. Societies around the world continue to grapple with the effects of white supremacist ideology. 

Today, the internet has created new potential for the global ideology to spread and provided a streamlined pathway to radicalization. Online, like-minded extremists have forged connections with few barriers and shared their views near instantaneously with devastating results. As far-right attacks have increased, white extremist killers around the globe have referenced or been inspired by previous attackers, revealing a transnational web of connections between perpetrators and the enabling role of the internet and social media.

Below, let’s explore the consequences far-right and white supremacist ideologies have not just on the United States but on societies around the globe.

What’s next?

Although the risk of terrorism in the United States is relatively small compared to other places, the recent increase in domestic terrorism has made clear that no country is entirely safe from these threats. Understanding how terrorism data is collected—and the trends it reveals—can help put threats in perspective both domestically and internationally, and help policymakers decide how to address them.