Skip to main content
Part of complete coverage from

Jihadist terrorism in America since 9/11

By Peter Bergen and David Sterman, Special to CNN
September 10, 2013 -- Updated 1154 GMT (1954 HKT)
<a href='http://www.cnn.com/2013/04/16/us/boston-marathon-explosions/index.html?hpt=hp_t2'>The bombings in Boston</a> on Monday, April 15, 2013, serve as a cruel reminder that the U.S. has seen other terror attacks on home soil. <a href='http://www.cnn.com/SPECIALS/us/boston-bombings-galleries/index.html'>See all photography related to the Boston bombings.</a> The bombings in Boston on Monday, April 15, 2013, serve as a cruel reminder that the U.S. has seen other terror attacks on home soil. See all photography related to the Boston bombings.
HIDE CAPTION
Terror attacks on home soil
Terror attacks on home soil
Terror attacks on home soil
Terror attacks on home soil
Terror attacks on home soil
Terror attacks on home soil
Terror attacks on home soil
Terror attacks on home soil
Terror attacks on home soil
Terror attacks on home soil
Terror attacks on home soil
Terror attacks on home soil
<<
<
1
2
3
4
5
6
7
8
9
10
11
12
>
>>
STORY HIGHLIGHTS
  • Authors: Since 9/11, al Qaeda hasn't carried out a successful attack in the U.S.
  • They say the threat has evolved into a danger of homegrown extremists launching attacks
  • Study finds that the number of attempted attacks has been declining
  • Authors: Could the Boston bombings have been prevented through better intelligence?

Editor's note: Peter Bergen is CNN's national security analyst and a director at the New America Foundation. David Sterman is a graduate student at Georgetown University's National Security Studies Program. This article is adapted from "Jihadist Terrorism: A Threat Assessment," a report for the Bipartisan Policy Center's Homeland Security Project written by Peter Bergen with Bruce Hoffman, Michael Hurley and Erroll Southers.

(CNN) -- We are about to mark the 12th anniversary of 9/11. Since then, al Qaeda and its affiliated groups haven't launched a successful attack in the United States.

The Boston Marathon bombings in April, however, serve as a reminder that the United States still faces a terrorism threat from disaffected U.S. citizens and residents who are influenced by al Qaeda's ideology.

So what is the status of this kind of threat?

Peter Bergen
Peter Bergen

The good news is that the number of "homegrown" jihadist extremists who have been indicted or convicted has steadily declined over the past few years, according to New America Foundation data. Where there were 41 cases in 2009, there have been six so far this year.

The number of individuals indicted for plotting actual attacks within the United States -- as opposed to other terrorism-related crimes such as raising money for a terrorist group -- also declined from 12 in 2011 to only three so far in 2013.

In recent years, extremists plotting attacks against the United States have also shown little, if any, connection to foreign groups. None of the 21 homegrown extremists involved in plots against the United States from 2011 to so far in 2013 is known to have received training abroad.

Of these extremists, only one, Tamerlan Tsarnaev, one of the alleged Boston bombers, is reported to have had contact with foreign militant operatives, but it remains unclear to what extent, if any, those contacts played a role in the Boston attack.

This lack of coordination between domestic extremists and overseas groups is likely the result of two factors. First, the ability of terrorist organizations to coordinate with extremists in the United States has been reduced by policing efforts inside the country and counterterrorism operations abroad.

Is terrorism still a threat to U.S. families?

Second, Internet use among jihadist extremists enables them to come into contact with extremist communities abroad and be radicalized without face-to-face meetings.

Of the 45 "homegrown" jihadist extremists who were indicted, convicted or killed from 2011 to now, 18 are known to have communicated with other extremists over the Internet or posted materials related to their radicalization online.

The shift to plotting by individuals who lack ties to foreign groups poses a distinct type of threat -- plots and attacks that are more difficult to detect but are also likely to be of a smaller scale. And because of the measures now in place to prevent the acquisition of precursor chemicals and materials suitable for making conventional explosives, homegrown extremists have also often struggled to produce effective bombs.

Before the Boston Marathon bombings, homegrown jihadists in the United States had shown little success at producing explosives. Joseph Jeffrey Brice -- who has professed admiration for Osama bin laden and Oklahoma City bomber Timothy McVeigh -- almost killed himself in April 2010 when a homemade bomb he was constructing exploded prematurely.

A month later, Faisal Shahzad's car bomb failed to explode in Times Square, even though he had received explosives training in Pakistan.

If the Tsarnaev brothers built the bombs used in the Boston attack without guidance from jihadists abroad, it suggests that the difficulties other "homegrown" militants have had building or detonating explosives may have been overcome. On the other hand, the Tsarnaevs' successful bombmaking could just as easily have been a fluke.

While the number of terrorism-related indictments fell between 2009 and 2013, the number of terrorist incidents has stayed about the same -- about one per year -- though not all of them have been lethal:

-- In June 2009, Abdulhakim Mujahid Muhammad killed a soldier outside a recruiting station in Little Rock, Arkansas.

-- Five months later, Major Nidal Malik Hasan shot and killed 13 people at Fort Hood in Killeen, Texas.

-- Shahzad's 2010 attempt to bomb Times Square was foiled when his bomb did not ignite properly.

-- Yonathan Melaku's drive-by shooting of military facilities in Northern Virginia in 2011 produced no casualties.

-- The Boston Marathon bombers killed four and wounded hundreds of others in April 2013.

The incidents carried out by homegrown extremists continue to be limited in their lethality, and major operations such as the 9/11 attacks are well beyond the skills of even the most capable domestic extremists.

Additionally, no homegrown jihadist militant in the United States is known to have acquired or used chemical, biological, radiological or nuclear (CBRN) weapons in the past twelve years. This point bears repeating, as there has been considerable overheated commentary on this subject over the past decade. Of the 221 individual cases of jihadist extremism since 9/11, not one case involved an allegation of CBRN acquisition, manufacture or use.

However, the fact that jihadist extremists in the United States have shown no interest in CBRN weapons does not eliminate the need for securing potential sources of chemical, biological and radiological agents.

According to a count by the New America Foundation, since 2001, 13 extremists motivated by right-wing ideologies, one left-wing militant and two individuals with idiosyncratic motives have deployed, acquired or tried to acquire chemical, biological or radiological weapons.

For example, William Krar and Judith Bruey, two anti-government extremists, possessed precursor chemicals for hydrogen cyanide gas, which they discussed deploying through a building's ventilation system. They were arrested in 2003 and later pleaded guilty.

The threat from homegrown extremists to the U.S. homeland has been constrained in recent years by a variety of security measures. According to data collected by the New America Foundation, family members of extremists and members of the wider Muslim American community provided useful information in the investigations of about a third of the homegrown jihadist extremists indicted or killed since 9/11.

Noncommunity members provided useful reports of suspicious activity in another 9% of homegrown extremist cases, while an informant or undercover agent monitored almost half of all homegrown extremists.

The Boston Marathon bombing, however, demonstrate the potential for these security measures to fail when plotters have few, if any connections, to known terrorist groups.

Looking forward, a concern about the Boston attack is whether it represents an intelligence failure that could have been avoided through a better implementation of existing policies or a new trend where "lone wolf" extremism is largely undetectable with the existing systemic checks in place.

The threat from homegrown extremists has changed substantially in the past three years, becoming the province of fewer individuals who are less connected to foreign groups than was once the case.

Whether this remains the case will depend on law enforcement being able to successfully adapt to confront the threat from disaffected U.S.-based individuals motivated by al Qaeda's ideology as well as whether the past few years' counterterrorism successes against al Qaeda overseas can be maintained.

Follow us on Twitter @CNNOpinion.

Join us on Facebook/CNNOpinion.

ADVERTISEMENT
Part of complete coverage on
December 25, 2014 -- Updated 0633 GMT (1433 HKT)
Danny Cevallos says the legislature didn't have to get involved in regulating how people greet each other
December 23, 2014 -- Updated 2312 GMT (0712 HKT)
Marc Harrold suggests a way to move forward after the deaths of NYPD officers Wenjian Liu and Rafael Ramos.
December 24, 2014 -- Updated 1336 GMT (2136 HKT)
Simon Moya-Smith says Mah-hi-vist Goodblanket, who was killed by law enforcement officers, deserves justice.
December 24, 2014 -- Updated 1914 GMT (0314 HKT)
Val Lauder says that for 1,700 years, people have been debating when, and how, to celebrate Christmas
December 23, 2014 -- Updated 2027 GMT (0427 HKT)
Raphael Sperry says architects should change their ethics code to ban involvement in designing torture chambers
December 24, 2014 -- Updated 0335 GMT (1135 HKT)
Paul Callan says Sony is right to call for blocking the tweeting of private emails stolen by hackers
December 23, 2014 -- Updated 1257 GMT (2057 HKT)
As Christmas arrives, eyes turn naturally toward Bethlehem. But have we got our history of Christmas right? Jay Parini explores.
December 23, 2014 -- Updated 0429 GMT (1229 HKT)
The late Joe Cocker somehow found himself among the rock 'n' roll aristocracy who showed up in Woodstock to help administer a collective blessing upon a generation.
December 23, 2014 -- Updated 2115 GMT (0515 HKT)
History may not judge Obama kindly on Syria or even Iraq. But for a lame duck president, he seems to have quacking left to do, says Aaron Miller.
December 23, 2014 -- Updated 1811 GMT (0211 HKT)
Terrorism and WMD -- it's easy to understand why these consistently make the headlines. But small arms can be devastating too, says Rachel Stohl.
December 22, 2014 -- Updated 1808 GMT (0208 HKT)
Ever since "Bridge-gate" threatened to derail Chris Christie's chances for 2016, Jeb Bush has been hinting he might run. Julian Zelizer looks at why he could win.
December 20, 2014 -- Updated 1853 GMT (0253 HKT)
New York's decision to ban hydraulic fracturing was more about politics than good environmental policy, argues Jeremy Carl.
December 20, 2014 -- Updated 2019 GMT (0419 HKT)
On perhaps this year's most compelling drama, the credits have yet to roll. But we still need to learn some cyber lessons to protect America, suggest John McCain.
December 22, 2014 -- Updated 2239 GMT (0639 HKT)
Conservatives know easing the trade embargo with Cuba is good for America. They should just admit it, says Fareed Zakaria.
December 20, 2014 -- Updated 0112 GMT (0912 HKT)
We're a world away from Pakistan in geography, but not in sentiment, writes Donna Brazile.
December 19, 2014 -- Updated 1709 GMT (0109 HKT)
How about a world where we have murderers but no murders? The police still chase down criminals who commit murder, we have trials and justice is handed out...but no one dies.
December 18, 2014 -- Updated 2345 GMT (0745 HKT)
The U.S. must respond to North Korea's alleged hacking of Sony, says Christian Whiton. Failing to do so will only embolden it.
December 19, 2014 -- Updated 2134 GMT (0534 HKT)
President Obama has been flexing his executive muscles lately despite Democrat's losses, writes Gloria Borger
December 18, 2014 -- Updated 1951 GMT (0351 HKT)
Jeff Yang says the film industry's surrender will have lasting implications.
December 18, 2014 -- Updated 2113 GMT (0513 HKT)
Newt Gingrich: No one should underestimate the historic importance of the collapse of American defenses in the Sony Pictures attack.
December 10, 2014 -- Updated 1255 GMT (2055 HKT)
Dean Obeidallah asks how the genuine Stephen Colbert will do, compared to "Stephen Colbert"
December 18, 2014 -- Updated 1734 GMT (0134 HKT)
Some GOP politicians want drug tests for welfare recipients; Eric Liu says bailed-out execs should get equal treatment
December 18, 2014 -- Updated 1342 GMT (2142 HKT)
Louis Perez: Obama introduced a long-absent element of lucidity into U.S. policy on Cuba.
December 16, 2014 -- Updated 1740 GMT (0140 HKT)
The slaughter of more than 130 children by the Pakistani Taliban may prove as pivotal to Pakistan's security policy as the 9/11 attacks were for the U.S., says Peter Bergen.
ADVERTISEMENT