Abstract: Measuring progress in irregular warfare without frontlines is always difficult. The various dimensions and multiple fronts of the United States’ ongoing campaign against terrorists make it an exceptional challenge. And much has changed since that campaign began 15 years ago. There has not been another 9/11-scale event. Although they attract followers, neither al-Qa`ida nor its progeny has become a mass movement. The constellation of groups claiming allegiance to them is far from an effective alliance, and the Islamic State has been contained. The leaders of al-Qa`ida depend heavily on exhortation to get others to fight, and the turnout is thin. On the other side of the ledger, the targeted groups have survived, their determination seems undiminished, and their ideology remains powerful. They are deeply embedded in a number of fragile, divided, conflict-ridden states. Persistent foes, they are able to operate underground and capable of comebacks if pressure on them subsides. The conflict will go on.
In December 2001, during testimony before a Senate Armed Services subcommittee, I was asked, “Mr. Jenkins, it has been three months since 9/11 and nothing more has happened. Are we through it yet?” I am certain that the senator was asking whether we were past the immediate danger of another 9/11-scale attack—the nation’s biggest fear—but I responded that this was likely to be a long contest lasting many years. Nearly 15 years on, we are not through it yet.
Nor is it clear how much further we have to go, although that is not surprising. Long wars have no signs telling us how many miles remain to the destination. The armies of Central Europe did not know in 1633 that they were halfway through the Thirty Years War. We will not know how close to (or far from) the end we were until the war is over.
But suppose I had been cursed with Cassandra’s powers of prophecy, and I had told the senators in 2001 that 15 years into the “Global War on Terror” (GWOT)—later called the more anodyne “Overseas Contingency Operations”—the United States would still be pursuing al-Qa`ida and its progeny, a dismaying reality, even though analysts at the time anticipated a long campaign.
Calling it the “long war” was disapproved at the same time the GWOT label was shelved, yet the conflicts in Afghanistan and Iraq have become the two longest wars in U.S. history. The effort has now occupied two U.S. presidents, each serving two four-year terms, and there is no question that President Obama will turn over command of the campaign to the next president.
Use of the term “war” created unrealistic expectations. Americans see warfare as a finite undertaking, but conflicts of this nature can go on for many years. It took the British a quarter-century to suppress the Irish Republican Army’s (IRA) terrorist campaign. Afghanistan’s current internal conflicts have continued in one form or another since at least the early 1970s—and some would assert even longer. Colombia’s insurgency has gone on for a half-century. Al-Qa`ida declared war on the United States in 1996, 20 years ago, but our jihadist foes see the struggle as one that began centuries ago and that will continue until Judgment Day. Some in the United States warn of an unending war.
The senators in 2001 would have been more pleased to hear that by 2016, America’s terrorist foes had not been able to launch another 9/11-scale attack—they had not even come close. Indeed, under a broad definition of “terrorism” that includes attacks by angry, sometimes mentally unstable individuals who embrace jihadist ideology only to rationalize their aggression, jihadist terrorists since 9/11 have managed to kill fewer than 100 people in the United States—all needless tragedies to be sure, but an average of six or seven jihadist-inspired murders a year in a country with an annual average of 14,000 to 15,000 homicides is a far better outcome than many people had feared in 2001.
The effort has come at a heavy cost. As of August 2016, the death toll for American military personnel in Operation Enduring Freedom and Operation Freedom’s Sentinel in Afghanistan stands at 2,383. Adding the 4,504 U.S. military deaths incurred in the Iraq War, which was portrayed by some in government and viewed by most Americans as an extension of the war on terror, raises the toll to nearly 7,000. Reports vary, but an estimated several thousand American civilian contractors also have been killed in the two wars, bringing the total to somewhere around 10,000. Another approximately 50,000 American military personnel have been wounded in the two wars.[a] Estimates of the total costs come to somewhere between $4 trillion and $6 trillion.[b] Would the senators have considered these costs to protect the homeland acceptable?
How Do We Measure Success?
Americans are pragmatists who want to see a return on their investments. And they are impatient. By now, we should have results, or at the very least, signs of progress. Are we winning or losing? Without frontlines, how do we measure? What do we count?
Progress is difficult to assess in this type of contest. There are no obvious metrics. Warfare itself has increasingly become a matter of manipulating perceptions. This is especially true in the realm of terrorism. Terrorist attacks are designed to be dramatic events, calculated to capture attention and create alarm, which will cause people to exaggerate the strength of the terrorists and the threat they pose.
The public sees every terrorist attack as a failure, a battle lost. Moreover, progress in degrading terrorists’ operational capabilities, slowing terrorist recruiting, or impeding terrorists’ financing seems slow, is not easily portrayed, and remains emotionally unsatisfying in the face of terrorist outrages. A framework of war allows for the possibility that the adversary will fight back, but every terrorist attack is seen as proof that counterterrorism efforts are not working.
Credibility is another problem. Premature claims by U.S. officials that suggest the mission has been accomplished or that the United States is within reach of defeating al-Qa`ida have eroded government credibility.
And in today’s highly partisan political environment, every attack is portrayed as evidence that the administration is incompetent, negligent, or worse. Every claim of progress is challenged. The political debate contributes to the atmosphere of fear.
Rising Totals of Terror Events Are Misleading
Even as the United States has waged war on terrorists, the total volume of terrorism worldwide, according to public databases, has increased since 2001. Is that evidence of failure?
Terrorism may increase or decrease for reasons that have nothing to do with current U.S. efforts to destroy specific terrorist groups. Some of the increase reflects better reporting. Also, in recent decades, terrorist tactics have become a mode of armed conflict that comes with warfare. As we engage terrorists militarily, they fight back with terrorist tactics. These attacks reflect the nature and intensity of the conflict; they are not necessarily a measure of counterterrorism failure.
If the United States were not pursuing these groups, they would have fewer opportunities to strike back, but that is no different from saying that American military efforts against the Axis Powers during World War II were responsible for the thousands of American soldiers killed in that conflict. And the presumption behind U.S. action against the terrorists is that since they have attacked the United States, they will continue to attack if the United States does not go after them. Leaving terrorists alone buys no immunity.
The Goalposts Have Moved
Assessments of progress also depend on how objectives are defined. In a long war, the objectives may change over time. The paramount concern immediately after the 9/11 attacks was the prevention of another attack on that scale or worse. U.S. efforts have thus far succeeded in this. But the aim was also to ultimately destroy the enterprise responsible for 9/11 for reasons of prevention, justice, and deterrence of other groups that might harbor similar intentions. Some progress has been achieved in this effort.
But soon after the war on terror began, U.S. officials began talking about taking down all terrorist groups that had American blood on their hands or that might pose a threat to U.S. security. Enlisting allies in America’s war on terror required including the terrorist organizations that threatened them as enemies. What began as a narrowly defined campaign against al-Qa`ida and its Taliban protectors soon turned into a broader campaign against a host of groups scattered across the globe.
In Afghanistan and other countries where jihadist banners have been raised, chasing terrorists has morphed into more ambitious counterinsurgency campaigns. Drone strikes and special operations make a purely counterterrorist effort possible, but these do not permanently alter the political landscape to eliminate potential terrorist strongholds.
U.S. officials today speak variously of destroying the most dangerous terrorist adversaries, protecting those in peril, preventing terrorist atrocities, denying terrorists safe havens, fixing failing states, filling ungoverned spaces, countering violent extremism, altering the conditions that contribute to radicalization and recruitment to violence, and attacking the root causes of terrorism. Attempting to achieve such aims guarantees a struggle lasting generations and a lot of frustrations.
The question most often asked by Americans is, “Are we safer now?” If the primary measure of progress is to make Americans safer, the authorities have done extremely well. Cooperation among intelligence services and law enforcement organizations worldwide has made the terrorists’ operating environment more hostile, while federal investigators and local police have uncovered and thwarted approximately 90 percent of the jihadist terrorist plots in the United States.[c] The risk of death at the hands of terrorists in the United States approaches lottery-winning odds. Add to that the fact that the annual rate of murders has fallen by 10,000 since the early 1990s, and the United States is a decidedly safer place.
Popular perceptions, however, are different. A spectacular terrorist attack—especially as terrorists increasingly focus their efforts on killing people in restaurants, train stations, airport terminals, tourist spots, supermarkets, nightclubs, music concerts, sports arenas, shopping malls, sidewalk promenades, churches, and other public places—makes the point that no one is safe. The random quality of the violence means that risk is everywhere.
The twin towers of the World Trade Center in New York City on September 11, 2001 (Henny Ray Abrams/AFP/Getty Images)
No Agreement on the Nature of the Enemy
The problem is not just that there are differing objectives. There is also debate about the identity of the adversary. Is it limited to the specific organizations described in the original authorization for the use of military force passed by the Congress, which later included those entities that became al-Qa`ida affiliates? The enemies list has since been expanded to include the Islamic State, a rebellious offshoot of al-Qa`ida, which brought in those professing loyalty to its leader. Must the United States therefore do something about Nigeria’s Boko Haram? Some, however, would say that the desire to remain politically correct prevents even naming the enemy—Islamic radicalism, the fundamentalist ideology that fuels the violence. Some go further and assert that it is Islam itself that must be confronted.
The changing political environment has brought in additional foes. According to some critics of current efforts, the United States should have employed military force to topple Bashar al-Assad in Syria and to bring down the nuclear-minded mullahs in Iran. Doing so, they assert, would have denied Iran and Russia any capability or opportunity to get in the way of the United States’ current efforts to destroy the Islamic State and other jihadist groups.
The Fear Remains
News coverage inflates the threat. Pundits offer competing visions of imminent doom. Assessments are driven not by what terrorists have done, but rather by what people fear they might do. Americans tend to be obsessed with decline and doom. To some extent, it seems that fears of terrorism condense broader national anxieties.
While to a certain extent, American apprehension about terrorism reflects the latest news headlines, terror operates in its own universe. According to a series of polls, one month after the 9/11 attacks, 41 percent of Americans said they thought it very likely that there would be another terrorist attack against the United States in the next several weeks. This percentage dropped over the years and remained low, often in single digits, until December 2015, when it jumped back to 33 percent. When asked in March if they worried about the possibility of a terrorist attack in the United States, 48 percent of Americans said they worried “a great deal.”
External Events Altered Strategic Calculations
The world does not stand still. In long wars, there are invariably events that, although external to the immediate conflict, can alter the contest and change strategic calculations. These have put us in a different place from where we started 15 years ago. In the current conflict, some of these, like the invasion of Iraq and the overthrow of Saddam Hussein in 2003, have been of America’s own making. These actions led to a long, bloody insurgency that distracted attention and resources from efforts in Afghanistan and the campaign against al-Qa`ida while breathing new life into al-Qa`ida’s propaganda line that aggressive infidels were bent upon conquering the Muslim world. The insurgency also created fertile ground for jihadist elements in Iraq who were never entirely suppressed and who later reemerged as the Islamic State.
Some point also to the consequences of the United States’ complete withdrawal from Iraq. They say that the absence of a U.S. military presence deprived the United States of the muscle to prevent the Iraqi government from creating a corrupt sectarian regime that alienated the Sunnis and replaced military commanders with less-competent loyalists. These critics assert that this rendered the Iraqi army a hollow force, which collapsed during the Islamic State offensive in 2014.
Al-Qa`ida’s supporters saw the 2008 global financial crisis as evidence that its efforts were about to bring down America, just as jihadist myth portrays the earlier campaign against the Soviet occupation of Afghanistan as the cause of the collapse of the Soviet Union. The second superpower did not fall, but the crisis underscored fiscal constraints, renewed domestic debates about military expenditures, and imposed new priorities on Western governments.
The most dramatic development was the Arab Spring. Al-Qa`ida’s claim of responsibility for the wave of political protests that spread across the Arab world was easily dismissed, but the resulting turmoil distracted authorities and gave hard-pressed jihadist groups some breathing space in places like Egypt’s Sinai. The protests also led to civil wars that completely changed the landscape of counterterrorist efforts.
In Libya, the political ferment quickly escalated, prompting foreign military intervention and the end of the Qaddafi regime. The result was a chaotic situation that jihadist elements quickly exploited. Faced with brutal government repression, the protests in Syria also turned violent, and by the end of 2011, Syria was at war with itself as the Islamic State, originally an offshoot of al-Qa`ida, declared its independence and launched a major military offensive across Syria and Iraq.
Events became even more complicated in September 2015 when Russia intervened militarily in Syria to assist the faltering Assad regime. Paralleling these developments, China began a significant buildup of its military presence in the South China Sea. Washington had already signaled its determination to “pivot” its attention away from Afghanistan and the Middle East to the Western Pacific. The renewed Russian threat to NATO and China’s threat to U.S. allies in the Western Pacific—historically core interests—complicated strategic calculations. The pursuit of al-Qa`ida and continued U.S. involvement in Afghanistan and the Middle East now has to be considered within this broader strategic context.
A Preliminary Balance Sheet
A thorough appreciation of the current situation requires assessing progress in different fields of action and different geographic theaters. Critics of the administration’s counterterrorist efforts will quarrel with this disaggregation, arguing that it compartmentalizes and therefore obscures the overall failure of U.S. counterterrorism efforts. In their view, the situation must be either better or worse: The continuing chaos in Syria, Iraq, and Libya; the proliferation of jihadist fronts; recruitment of foreign fighters; the growing volume of terrorism worldwide; and recent spikes in terrorist attacks in Europe and the United States indicate that it is worse.
But a closer examination of each of these aspects suggests a more complicated balance sheet. In some areas, counterterrorism efforts have been successful; in other areas, less so. And for every plus or minus entry, there is a “however.” Moreover, as shown in the preceding discussion, the situation has been and continues to be dynamic.
On the plus side, our worst fears have not been realized. There have been no more 9/11s, none of the worst cases that post-9/11 extrapolations suggested. The 9/11 attacks now appear to be a statistical outlier, not a forerunner of further escalation. Terrorists have not used weapons of mass destruction, as many expected they would do. (At least they have not used them yet, many would add.) While the Islamic State appears to have recruited some chemical weapons specialists, the terrorist arsenal remains primitive, although lethal within bounds.
Contrary to the inflated rhetoric of some in government, the operational capabilities of al-Qa`ida and the Islamic State remain limited. Both enterprises are beneficiaries of fortune (they would argue, of “God’s will”). They are successful opportunists. The Islamic State’s military success in Syria and Iraq reflects the collapse of the government’s forces, not military prowess. With its legions of foreign fighters and deep financial pockets, the Islamic State theoretically could launch a global terrorist offensive, but the surge would probably be brief. This is not, as some have suggested, World War III.
Neither al-Qa`ida nor the Islamic State has become a mass movement, although both organizations attract sympathy in Muslim countries. The vast majority of Muslims polled over the years express negative views of jihadist organizations, but a significant minority expresses favorable views of al-Qa`ida and, more recently, of the Islamic State. While Usama bin Ladin’s reputation declined in some Arab countries, 2013 polling found 13 percent of Muslims polled in Arab, African, and Asian countries still held favorable attitudes of al-Qa`ida. The declaration of a caliphate by the Islamic State in 2014 created excitement among extremists worldwide and injected new life into some moribund groups. According to polling in 2015, from zero to 14 percent of the people in the countries polled had a favorable view of the Islamic State, with Lebanon (a Shi`a-majority country) at zero and Nigeria at 14 percent. Although the percentage of favorable ratings for the terrorists is generally low, it still represents large numbers of people—a deep reservoir of support.
The National September 11 Memorial and One World Trade Center in New York City (Cem Ozdel/Anadolu Agency/Getty Images)
The constellation of jihadist groups is not as meaningful as it appears to be. Competing for endorsements, al-Qa`ida and the Islamic State have attracted declarations of loyalty from local groups across Africa, the Middle East, and Asia and have established a host of affiliates, provinces, and jihadist footholds. This is growth by acquisition and branding. A lot of it is public relations. Many of these groups are the products of long-standing local grievances and conflicts that would continue if there were no al-Qa`ida or Islamic State. Some are organizational assertions that represent only a handful of militants. The militants share a banner but are, for the most part, focused on local quarrels rather than a global jihad. There is no central command. There are no joint operations. The groups operate autonomously. Their connections in many cases are tenuous, although, with time, they could evolve into something more connected. The split between al-Qa`ida and the Islamic State has divided the groups. A number of them are beset by further internal divisions.
Like all terrorists, jihadis can kill, destroy, disrupt, alarm, and oblige governments to divert vast resources to secure against their attacks, but terrorists cannot translate their attacks into permanent political gain. Yet this is not the way they measure things. They tend to see their mission as continuing operations to demonstrate their commitment and awaken others.
The Islamic State is losing territory and can be defeated. With coalition air support and other external assistance, government forces in Iraq and U.S.-backed Kurdish and Arab fighters in Syria have been able to retake territory held by the Islamic State. Progress is slow, though faster than many analysts initially anticipated. This is not just a military challenge; it is also an effort to put something in place to govern recovered towns and cities.
Al-Qa`ida Central’s command has been reduced to exhorting others to fight. The Islamic State has made very effective use of social media to reach a broader audience. Its advertisement of atrocity as evidence of its authenticity appears to have been a magnet for marginal and psychologically disturbed individuals. Jihadist ideology has become a conveyer of individual discontents.
Continuing calls on local terrorist supporters in the West to take action have thus far produced only a meager response. Measured against other recent terrorist campaigns, the level of violence has been low. During the eight years of the Algerian War, more than 5,000 people were killed in France.[d] More than 3,600 died during the IRA’s terrorist campaign. More than a thousand were killed during the Basque separatists’ struggle in Spain.[e] With larger volumes of homegrown terrorists and returning foreign fighters, Europe faces a greater threat than does the United States. An Islamic State network that combined returning fighters with a domestic radical underground carried out a two-year terrorist campaign that included the deadly attacks in Paris in November 2015 and Brussels in March 2016. But most of the attacks in Europe have been one-offs. However, these can be lethal, as seen in the July 14 attack in Nice. These terrorist attacks have also provoked a backlash, which rightwing extremists have exploited, raising the specter of civil strife.
In the United States, the number of homegrown terrorists remains a fraction of the numbers seen in Europe. All of the recent Islamic State-inspired attacks and plots uncovered in the United States have been the products of a single individual or a tiny conspiracy with no direct connections to any organization. Nonetheless, these attacks create alarm.
On the minus side, the targets of the American campaign have survived U.S. counterterrorism efforts. Al-Qa`ida has survived intense U.S.-led campaigns for 15 years, and now the Islamic State has survived them for two years. Al-Qa`ida and the Islamic State have been cornered, not crushed. No victory is final. These organizations have proven resilient and adaptive. They have morphed to meet new circumstances and exploit new opportunities, and they will continue to do so. The threat remains.
Their determination is undiminished. We cannot yet claim to have dented the determination of the jihadis to continue their armed struggle. They view strategy as process-oriented rather than progress-oriented, meaning that they derive benefit from commitment, regardless of immediate outcomes, which remain in God’s hands. They believe that they are on the side of God and we are not, and therefore, in the long run, they believe they will prevail.
The jihadis have a powerful ideology that arouses extreme emotion and devotion. We cannot deny the appeal of the jihadist ideology, especially to persons predisposed by other collective grievances or personal problems. But on the plus side, the low numbers suggest that the ideology has gained little traction in America’s Muslim communities. Personal crisis is the dominant attribute of America’s jihadis.
The Taliban has been driven from power, but it remains a formidable foe and will not be tamed. The continued deployment of U.S. forces will be necessary to prevent the Taliban from regaining control of much of Afghanistan and preventing al-Qa`ida from a comeback by riding their coattails.
The fighting in Syria and Iraq will go on for the foreseeable future. Foreign powers have much at stake, but they have conflicting agendas and cannot impose peace from the outside. For local belligerents, the contests have become existential.
Faced with loss of its territory, the Islamic State will not quit. A long insurgency is likely to follow. The leaders of the Islamic State fought clandestinely for years in Iraq and could go underground again to continue the struggle. They could relocate to Libya or another jihadist stronghold, creating a mobile Islamic State. Or they could try to carry out some sort of dramatic attack that alters perceptions or changes the dynamics of the conflict. This could take the form of a Tet-style offensive in Baghdad or Damascus, a terrorist campaign that shakes the Saudi kingdom, or a dramatic act of terrorism abroad that provokes foreign intervention.
Syria and Iraq will remain fragile states, arenas of international competition, and sources of regional instability and continued violence. Current partitions are likely to persist. National institutions have eroded. Power on the ground has shifted to militias under local or foreign control and to the rebel formations. Neither government can restore authority throughout its national territory without significant foreign assistance, and they may not be able to do so even with such assistance, although Iraq may come closer. The Shi`a and Kurdish portions of Iraq and the Alawite-dominated bastion in western Syria may be economically viable, but the poorer and less-populated Sunni areas of both countries currently dominated by the rebels and the Islamic State could become persistent badlands.
The world will be dealing with the effluents of the conflicts in Syria and Iraq for years to come. The tens of thousands of foreign fighters who have joined the Islamic State and other jihadist groups have no future under Iraqi or Syrian government authority and cannot survive in an underground campaign. They will likely migrate to other jihadist formations, try to establish new jihadist fronts, or return home—some traumatized, some disillusioned, but some determined to continue their armed struggle. The destruction of the Islamic State could bring about a spike in terrorist activity by its veterans worldwide.
Refugees will pose a long-term challenge to society and security. Syria’s brutal counterinsurgency strategy has generated huge refugee flows. The refugees will not be able to return for the foreseeable future but are permanently displaced. Nor, given their volume, can they be easily absorbed by neighboring countries with small populations and delicate sectarian balances. Migrants and at least some foreign fighters have exploited the refugee flow to Europe. Most of the refugees will build new homes, but the refugee flow includes a large proportion of single young men, always a problematic demographic and especially so coming from violent environments and having little education. They will not easily find work and assimilate. Some will drift into crime, while others may be targets of radicalization.
The United States faces a multi-tiered threat. While the threat of large-scale attacks by terrorist teams infiltrating the country seems to have diminished, authorities still confront the problem of returning foreign fighters, although the numbers are far less than those in Europe, and returning American jihadis will not have a local underground to provide them with hideouts and assistance. The primary threat will come from the ability of al-Qa`ida and the Islamic State to inspire attacks by self-radicalized individuals, as well as emotionally disturbed persons seeking attention by associating themselves with a terrorist cause.
The United States is better organized and equipped to combat terrorism, but its citizens remain fearful. The United States’ frightened, angry, and divided society remains the country’s biggest vulnerability. Progress in degrading al-Qa`ida’s capabilities or dismantling the Islamic State is almost completely divorced from popular perceptions. Rather than appeal to traditional American values of courage, self-reliance, and sense of community, our current political system incentivizes the creation of fear.
So, to update my 2001 response to the Senate committee, after 15 years a lot has changed, there has been progress, and Americans are safer. But, no, we are not through yet.
Brian Michael Jenkins is a senior adviser to the president of the RAND Corporation and author of Will Terrorists Go Nuclear? A former Green Beret, he served on the White House Commission on Aviation Safety and Security and as an advisor to the National Commission on Terrorism from 1999 to 2000. Follow @BrianMJenkins
[a] These military casualty numbers are derived from the U.S. Department of Defense and iCasualties.org. The total number of fatalities varies slightly between the two sources. The estimate of civilian contractor deaths comes from the Defense Base Act Compensation Blog.
[b] A number of academic studies have been published including a 2013 report by Linda J. Bilmes of Harvard University’s Kennedy Center, which estimated the total projected costs of the two conflicts at more than $4 trillion, including future costs of caring for veterans and paying interest on borrowed money. Bilmes, “The Financial Legacy of Iraq and Afghanistan: How Wartime Spending Decisions Will Constrain Future National Security Budgets,” Harvard Kennedy School, March 2013. Obviously much depends on what costs are included. In a 2015 report for the Center for Strategic and International Studies, Anthony H. Cordesman estimated the total cost of the two wars at between $4 and $6 trillion. Cordesman, “The FY2016 Defense Budget and U.S. Strategy, Key Trends and Data Points,” Center for Strategic and International Studies, March 6, 2015.
[c] According to the author’s own research, there have been between 80 and 90 homegrown jihadist terrorist plots in the United States since the 9/11 attacks. This total excludes externally mounted attacks like the 2001 attempt to sabotage an airliner bound for the United States via a shoe bomb or the 2009 sabotage attempt by Umar Farouk Abdulmutallab, the so-called underwear bomber. Of these, only nine plotters were not intercepted before carrying out their attack. There were a few other cases where jihadist inspiration blended with mental illness.
[d] This includes casualties from violence between Algerian militants inside France as well as terrorist attacks on French targets. See “Algeria, FLN, Country Studies” in Helen Chapan Metz ed. Algeria: A Country Study (Washington: GPO for the Library of Congress, 1994).
[e] According to the Global Terrorism Database, 1,047 known fatalities resulted from the Basque separatist struggle in Spain between December 1970 and September 2014. See Global Terrorism Database, START, University of Maryland.
 “Terrorism in the United States,” Gallup, 2016.
 Helene Cooper and Eric Schmitt, “ISIS Detainee’s Information Led to 2 U.S. Airstrikes, Officials Say,” New York Times, March 9, 2016.
 “Muslim Publics Share Concerns about Extremist Groups,” Pew Research Center, September 10, 2013.
 Jacob Poushter, “In nations with significant Muslim populations, much disdain for ISIS,” Pew Research Center, November 17, 2015.
 Seamus Kelters, “Violence in the Troubles,” BBC, February 2013.