We're now well into the second decade of the "war on terror." But who, exactly, are we fighting? And why do they want to hurt us?
To see the big picture, BuzzFeed News has crunched the numbers on deaths and injuries caused by terrorist attacks on U.S. soil, categorizing them by the extremist ideologies involved.
Militant Islamist terrorism dominates, but extremists from the political right also pose a potent threat. And our analysis contains a surprising message: Although another devastating event like 9/11, the Oklahoma City bombing, or last week's attacks in Paris could change everything, violent extremism has actually been in decline.
Two decades of casualties reveal the extreme ideologies that threaten American lives.
In the aftermath of 9/11, it has become easy to equate terrorism with violent Islamists. But this chart, showing the number of deaths and injuries caused by terrorist attacks in the U.S. from 1995 to 2014, paints a more complex picture.
Yes, those waging a violent jihad against America are responsible for the largest number of casualties by far — but they are not alone.
To tally attacks, deaths, and injuries, BuzzFeed News used the most authoritative academic source, the Global Terrorism Database (GTD) maintained by START, the National Consortium for the Study of Terrorism and Responses to Terrorism, at the University of Maryland. To help make sense of the numbers, we attributed the 97 attacks involving casualties to broad ideological categories, consulting with Erin Miller, a criminologist at START who manages the GTD.
Terrorism is notoriously difficult to define. The GTD defines it as "the threatened or actual use of illegal force and violence by a non-state actor to attain a political, economic, religious, or social goal through fear, coercion or intimidation." By this definition, the two most prolific U.S. terrorist groups over the past 20 years are the Earth Liberation Front and the Animal Liberation Front, each responsible for more than 60 incidents.
But environmental and animal rights extremists have mostly targeted institutions, not individuals — so although many buildings have burned, these terrorists are responsible for only two injuries and one death since 1995.
Extremists motivated by their opposition to abortion have pursued a deadlier brand of single-issue terrorism. The most notorious was Eric Rudolph, now serving life without parole for bombing the Centennial Olympic Park in Atlanta during the 1996 Olympics, killing one spectator and injuring 110 more. Rudolph acted in the name of the Army of God, later stating that he wanted to "embarrass the Washington government in the eyes of the world for its abominable sanctioning of abortion on demand."
The attacks BuzzFeed News categorized as Islamist terrorism include some committed by Muslims who may have been motivated as much by opposition to U.S. foreign policy and military actions as by religion. These include the 2013 Boston Marathon bombers, Tamerlan and Dzhokhar Tsarnaev. Although the FBI stressed the pair's extreme Islamist beliefs, the note scrawled by Dzhokhar on the boat in which he hid after a police shootout claimed he had acted in retribution for the wars in Iraq and Afghanistan.
There are clear parallels with the bloodiest incident in the nationalist category: In 1997, Ali Hassan Abu Kamal shot seven people, killing one, on the observation deck of the Empire State Building. He apparently wanted to punish the United States for its support for Israel in its conflict with the Palestinians.
Right-wing extremists, meanwhile, divide into two broadly distinct groups. One, typified by the 1995 Oklahoma City bomber Timothy McVeigh, is driven by distrust of the U.S. federal government.
Then there are the white supremacists. They include Wade Michael Page, who stormed the Sikh temple in Oak Creek, Wisconsin, in August 2012, killing six worshippers and wounding four more. When the GTD is updated for 2015, it will also include the murder of nine black members of the Emanuel African Methodist Episcopal Church in Charleston, South Carolina, gunned down in June by 21-year-old Dylann Roof, seen posing online with the Confederate flag.
Despite the best efforts of the FBI and researchers at START, the ideological motivation for some incidents remains obscure. These include the anthrax-tainted letters that killed five people and sickened another 17 in 2001, further terrorizing a jittery nation in the aftermath of 9/11.
A handful of high-profile incidents dominate the casualty figures.
Here are those numbers again, this time shown as a mosaic. Each rectangle is an individual incident, scaled according to the number of deaths and injuries involved (hover or tap on the chart for more information about each).
Viewed in this way, it's clear how the 9/11 attacks, and the truck bomb that destroyed the federal building in Oklahoma City in April 1995, dominate the casualty figures. In reality, 9/11 dominates even more than shown here, because the numbers for the destruction of the World Trade Center include only the confirmed dead. No one knows for sure how many people were injured in that attack — although we do know that emergency rooms geared up on 9/11 for a wave of casualties that mostly never arrived, because so many of the victims were killed outright.
Start digging into individual incidents, and it becomes clear why terrorism is so difficult to study. Was Nidal Hasan, the U.S. Army psychiatrist who in 2009 killed 13 and injured 30 more at the Fort Hood base in Texas, a committed jihadi? Or should he be seen as a mentally disturbed individual who has more in common with other American mass shooters?
Hasan had communicated by email with Anwar al-Awlaki, alleged to be a senior recruiter for al-Qaeda. But when prosecuting Hasan, the Pentagon described his actions as "workplace violence." (BuzzFeed News grouped him with the militant Islamists.)
Right-wing extremists skew older than militant Islamists — and are less likely to be stopped before they attack.
To get a more detailed profile of the people who are willing to harm Americans to further their ideological goals, BuzzFeed News turned to data compiled by the New America think tank on 497 extremists indicted or killed in the U.S. since 9/11 — including 314 militant Islamists and 140 right-wing extremists. (New America included a handful of anti-abortion extremists in the latter category.)
Terrorists are mostly angry young men — just 6.7% of New America's militant Islamists, and 9.3% of the right-wingers, were women.
Right-wing extremists, with a median age of 35 at arrest or death, tended to be a little older than jihadis, who had a median age of 26. The right-wingers include the white supremacist Frazier Glenn Cross, aka Frazier Glenn Miller, who was 73 in April 2014 when he opened fire at the Overland Park Jewish Community Center in Kansas, killing three people.
There is one obvious difference between the militant Islamists and the right-wingers in New America's data — just 7% of the Islamists were involved in an incident that came to fruition, compared to 48% of the right-wingers. Most of the Islamists were arrested before they could attack, or for offenses such as funding terrorist groups; 18% of them were charged with planning to fight for terrorist organizations overseas.
One interpretation of this difference is that right-wingers are more "successful" terrorists. But these numbers also provide support for claims that the FBI has been aggressively pursuing Islamist extremists — in part by luring jihadist sympathizers into committing criminal acts — while neglecting the threat posed by the extreme right.
Prominent among these critics is Michael German of New York University's Brennan Center for Justice, who for many years worked as an undercover FBI agent infiltrating extremist groups. He argues that the right-wing threat is even greater than the data shows, because hate crimes often don't get defined as terrorism.
"It's this inability to look at acts of political violence as equivalent," German told BuzzFeed News.
Violent extremists in America are mostly U.S. citizens.
Fears about terrorism often get pulled into the debate over immigration — Republican presidential candidate Donald Trump, for example, has claimed that refugees fleeing Syria could be a "Trojan horse" for ISIS. And in the wake of last week's attacks in Paris, other contenders for the GOP nomination have called for a rethink of plans to take in Syrian refugees.
The majority of extremists in the New America data are U.S. citizens, but the numbers for the militant Islamists provide talking points for both sides of the immigration debate.
A 2011 survey conducted by the Pew Research Center found that 37% of Muslims in the U.S. were citizens by birth, 44% were naturalized citizens, and 19% were noncitizens of various types.
By comparison, New America's tally of militant Islamists shows 46% born in the United States, 23% naturalized citizens, and 31% noncitizens. So noncitizens and — to some extent — U.S. citizens seem to be overrepresented among the small minority of Muslims attracted to violent extremism, while naturalized citizens are underrepresented.
Terrorist incidents are actually in decline, but beware the next 9/11.
This chart may surprise you. According to the GTD, the number of terrorist incidents in the U.S. has declined markedly since the 1970s, when the most active groups included left-wing extremists such as the New World Liberation Front and the Weather Underground Organization.
The most dangerous organizations back in the '70s, judged by casualties inflicted, included the Black Panthers and the FALN, a Marxist group fighting for Puerto Rican independence.
Since then, the pattern of terrorism has changed. Although there are fewer attacks than before, and those causing casualties are more infrequent, we live in fear of devastating attacks that can claim hundreds or even thousands of lives.
The three tallest columns on the chart above are driven by 9/11, the 1995 Oklahoma City bombing, and the 1993 World Trade Center bombing, which killed six and injured more than 1,000. And if you're wondering, 1984's high casualty count was due to America's first experience with bioterrorism — when followers of the Indian mystic Bhagwan Shree Rajneesh contaminated salad bars in The Dalles, Oregon, with salmonella, infecting more than 750 people.
Today, food hygiene is the least of the FBI's worries. The bureau's focus is on preventing attacks from happening, rather than investigating incidents after they occur. The Paris attacks have underlined the importance of this mission.
"Prosecuting someone after they've killed 3,000 people is not a measure of success," Michael Steinbach, assistant director of the FBI's Counterterrorism Division, told BuzzFeed News.
The challenge is how to do that without infringing the civil liberties of people whose views we find extreme — but who have a constitutional right to express them.