Key Trends in the Uncertain Metrics of Terrorism

It is now some 15 years since 9/11, the United States has not only conducted a constant campaign against terrorism since that time, but has been at war with violent Islamist extremists in Afghanistan, then Iraq, and then Syria. It has gone from counterterrorism to a mix of counterterrorism and counterinsurgency in these three states where no meaningful boundaries exist between them while the United States is increasingly a partner in counterterrorism efforts with nations in Europe, Africa, and Asia and throughout much of the Islamic world.

Virtually all of the data available indicate that these threats to the United States and its allies remain critical and that the geographic scope and intensity of terrorism continues to increase. At the same time, there are critical problems and shortfalls in the data available, a near total lack of credible unclassified data on the cost and effectiveness of various counterterrorism efforts, and critical problems in the ways the United States approaches terrorism.

The Burke Chair at CSIS has updated a graphic survey of reporting from different officials, media, and research centers on the recent trends in terrorism and key related factors. This survey is available on the CSIS website, and is entitled Comparing Estimates of the Key Trends in the Uncertain Metrics of Terrorism. It is available on the CSIS web site at

The updated version contains updated chronologies and other material to reflect the recent ISIS/ISIL/Daesh attacks on targets in Belgium and Turkey, and the size and structure of the U.S. homeland defense efforts presented in the FY2017 budget request, as well as related U.S. military operations.

Critical Limitations in the Data and Portrayal of Key Trends

It should be stressed, however, that the limitations in the data available and in current unclassified methods of analysis and reporting discussed in this survey still reveal serious problems in the ways in which given sources present given trends, and in the data on which these portrayals are based. They need to be carefully compared to understand key differences in estimates and analyses, and many data are presented without any clear assessment of uncertainty and source and are suspect in many ways.

These issues have been examined previously in a Burke Chair study entitled, The Critical Lack of Credibility in State Department Reporting on the Trends in Global Terrorism: 1982-2014, . This study only covered a small part of the issues in the current survey, however, and focused only on the critical problems in the unclassified data, and the resulting trend analyses produced by using the National Counterterrorism Center (NCTC) and START databases.

The trends, methods of analysis, and focus on given issues and problems highlighted in this survey reveal a much wider range of problems in the data, and indicate that there may well be even more critical problems in the ways the U.S. government, other governments, and NGOs approach terrorism and counterterrorism:

  • The definition of “terrorism” used is often not stated, politicized, and/or confuses “terrorism” with insurgency, internal conflicts, and low intensity conflict.
  • The NCTC no longer reports numbers or patterns on an unclassified basis. There now are no official U.S. government reports presenting unclassified data reporting on the global trends in terrorism.
  • The FBI no longer issues updated charts and tables on terrorism in the United States on its website. Its website refers the user to the NCTC’s website and its Counter Terrorism Guide, which no longer has any meaningful data.
  • The Director of National Intelligence’s “Worldwide Threat Assessment of the US Intelligence Community” discuses terrorism in broad trends, but provides virtually no quantitative data.
  • RAND has stopped providing public access to its database on terrorism.
  • The START Global Terrorism Database (GTD) database—which is used by the State Department in presenting a statistical annex to its annual country reports on terrorism—comes as close to an official source as any available. It must rely on media reporting of widely differing quality and historical continuity for its estimates, however, and does not distinguish clearly between terrorism and insurgency, or violence emerging from internal conflicts driven by factors like sect, ethnicity, tribe, and region.
  • START makes the unofficial character of its data clear in its literature:

The data presented here are drawn from the Global Terrorism Database (GTD). The GTD contains information on more than 140,000 terrorist incidents that have occurred around the world since 1970. For more information about the GTD, visit …The GTD is a project of the National Consortium for the Study of Terrorism and Responses to Terrorism (START). START aims to provide timely guidance on how to reduce the incidence of terrorism and disrupt terrorism networks, as well as enhance the resilience of society in the face of terror. The National Consortium for the Study of Terrorism and Responses to Terrorism (START) is supported in part by the U.S. Department of Homeland Security Science and Technology Directorate’s Office of University Programs through a Center of Excellence program led by the University of Maryland. START uses state‐of‐the‐art theories, methods and data from the social and behavioral sciences to improve understanding of the origins, dynamics and social and psychological impacts of terrorism. For more information, contact START at or visit…This research was supported by the Science and Technology Directorate of the U.S. Department of Homeland Security through awards made to START and the author. The views and conclusions contained in this document are those of the author and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Department of Homeland Security or START.

  • Other sources differ sharply in content and estimates.
  • Most sources do not attempt to estimate uncertainty; many do not explain methodology and source of data.
  • Reporting on state-sponsored terrorism is extremely erratic and is limited largely to criticism that focuses on a few hostile powers in ways that are highly politicized and lacking in detail. No effort is made to estimate state covert action or terrorism against given elements of its own population.
  • As a result, excessive repression in the name of counterterrorism, and state repression that amounts to de facto state terrorism, are not reported as terrorism even when they have such impacts. The grave acts committed in the name of counterterrorism by various states—many U.S. partners and allies—are officially reported on only in the State Department’s annual human rights report and by human rights NGOs.
  • As a result, virtually all reporting focuses on non-state actors.
  • No clear basis exists for addressing war crimes and the impact of conflict vs. terrorism and many estimates are politicized.
  • Most data on terrorism are nationwide, regional, or global. The impact of key regional, ethnic, sectarian, tribal, and other internal conflicts may or may not be reported as terrorism and are not addressed by source, cause, or reasons for choosing given targets.
  • No reliable data exist on foreign volunteers, on international flows of terrorist activity, or on the overall patterns in extremism.
  • No clear source or method exists for estimating the impact of terrorism on creating refugees, internally displaced persons, lasting human and humanitarian impacts, collateral damage, and economic impacts.
  • Casualty data are usually extremely uncertain. Most only attempt to count casualties caused by non-state actors. They too confuse terrorism with insurgency and internal power struggles, and many sources only address killed, rather than injured or wounded.
  • There is no way to estimate the impact of terrorism in areas dominated or controlled by various groups, and once again, insurgent groups the U.S. sees as enemies are often labeled as “terrorists” regardless of the fact that they are insurgents using forms of irregular warfare which are not “terrorism” per se and/or are reacting to abuses by the governments they are challenging.
  • Incident counts and casualty data are erratic, and the other impacts of extremism and terrorism such as intimidation, extortion, torture, and misuse of the justice system cannot be quantified and no reliable methodology exists for estimating areas of geographic influence.
  • Aside from chronologies—which differ sharply from source to source—reporting by time and on the areas affected is erratic and uncertain.
  • Reporting at best covers half of the challenges posed by counterterrorism. There is no clear source of comparative data on the size, cost, nature, and comparative effectiveness of various counterterrorism efforts by country and international organization.
  • Only limited snapshots exist of the factors that cause terrorism, insurgency, and internal violence. Key factors like population pressure, “youth bulges,” underemployment and unemployment, critical problems in governance, corruption, barriers to development, critical problems in income distribution, cronyism and nepotism, repression and failed rule of law, internal discrimination, and alienation of key segments of the population, are rarely addressed and often only in the form of special pleading.
  • Comparative assessment of efforts to address the level of Islamic extremism in given countries and areas—and to address the efforts to counter such extremism on a religious, ideological, and political basis—also are limited snapshots of part of the problems and efforts involved. Many are special interest efforts supporting a given proposed approach or solution.
  • Some broad measures of the cost-effectiveness of the U.S. counterterrorism effort—and its strengths and weaknesses—are provided by the Department of Homeland Security (DHS), but these cover only part of the U.S. domestic effort, however, and do not cover overseas contingency operations. (For 2015 Examples, see , , and

The Contents of the Survey

The survey has the following major sections:

Global Patterns of Attack

This section compares work done by Vision of Humanity, START, and the National Consortium for the Study of Terrorism and Responses to Terrorism to examine the trends in numbers of attacks and their lethality, both globally and by country and region. It also shows trends by source and perpetrator, by tactic and target, and by whether the target is a government or private citizens and property.

These trends generally reflect a sharp rise in every aspect of terrorist activity, but some of this rise comes from counting attacks and casualties that seem more driven by different insurgencies and conflicts between sects, ethnic groups, and factors like tribal conflict. The counts are also all based on media reports rather than intelligence estimates, and only count actions by non-state actors and not that of states.

Comparison of the START database with past NCTC estimates raises serious questions about how closely the START data track with NCTC data, and how closely the incidents reported in media sources compare with those by the intelligence community.

There also are no uncertainty estimates; only limited data on the full range of sources and methods, and many of the data have a very improbable level of precision. It is not clear which source of data—if any—is correct. These issues badly need to be resolved by the U.S. government. It is impossible to assess what kind of unclassified reporting is most correct without the resources and access to classified data that only governments possess.

The Rising Impact of the World’s Muslims and the Need for Strategic Partnerships in Counterterrorism

This section focuses on the potential future impact of Islamic terrorism, and draws on work by the Pew Research Center to highlight the sharp rise taking place in the world’s number of Muslims. The Pew Research Center projects a rise from some 1.6 billion in 2010 to 2.8 billion in 2050, drawing on a study that does examine uncertainty and clearly shows its sources and methods.

It should be stressed that the vast majority of Muslims oppose violence and extremism, but these data also must be interpreted in the light of reporting by the UN Development Reports, Arab Development Reports, World Bank, IMF, and Transparency International that shows that the countries where the Muslim population is increasing sharply often suffer weak and corrupt governance, major barriers to business and development, sharp population growth and major problems in job creation and employment, and poor income distribution.

These problems are often compounded by serious sectarian and ethnic tensions, and by the social impact of hyperurbanization, weak state sectors and enterprises, and a lack of agricultural reform.

Taken in combination, these pressures warn that extremism in some form is likely to persist for the next few decades almost regardless of what happens to current extremist groups.

Terrorism in Violent and War-Torn Countries

Some sources like Vision of Humanity do recognize that the state is often the source of the violence reported, and that terrorism and insurgency cannot be validly portrayed without a net assessment of the role of the state in causing internal violence and imposing its own form of terrorism.

Like the previous section on Global Patterns of Attack, many of the trends and data in this section do reflect a valid increase in terrorism and the level of incidents and casualties. They also, however, include many cases where the violence involved is actually from an insurgency and not from terrorism per se. In many cases, only violence by non-state actors—not the state or its allies—is measured. As UN casualty reporting on the wars involved has shown, the failure to report state and allied violence and casualties is a fundamentally dishonest and misleading portrayal of the conflicts involved.

Many of the data are also extremely uncertain, and fail to illustrate the fact that the causes of such violence have roots in critical tensions and conflict between different sects, ethnic groups, tribes, and regions—as well as critical failures and inequities in governance, economic policies, and human development.

At the same time, the data are broadly valid in portraying the main locations of terrorism, insurgency, and internal violence as being driven by a growing battle for the future of Islam—and the by threat posed by still marginal violent Islamic extremist groups. It is also all too clear that if these trends were updated to include 2015, the levels of violence would not only be higher, but would also include a steadily growing number of countries.

The Growing Role of ISIS (ISIL, Daesh, Islamic state)

This section is somewhat artificial in that the maps and chronologies focus on ISIS to the exclusion of the much wider range of extremist movements, insurgencies, and internal conflicts shown in earlier sections. This reflects critical problems in governmental, media, and independent research activity that tend to concentrate on the most immediate and visible threat rather than the overall patterns involved and their causes.

It also has the effect of implying that the main threat of terrorism is ISIS, and defeating ISIS can solve the problem. The previous sections show all too clearly that even a victory that resulted in the total defeat of ISIS as a protostate, and its break-up as an organization, would soon see other movements take its place—just as ISIS has to some extent replaced Al Qaida.

Any such defeat would also leave many present ISIS fighters and cadres active, and at best address the threat in Iraq and Syria without addressing any of the critical sectarian and ethnic differences, and failures in governance and development, which have led to sustained violence in both countries. It would do nothing to address the forces in the other countries where ISIS has gained affiliates that can immediately change their affiliation or will soon be replaced by other movements.

The summary chronologies presented in this section do illustrate the fact that broad estimates of trends in attacks and casualties do little to reveal the patterns in terrorist and insurgent attacks. At the same time, the chronologies presented are only part of a long series of different efforts and the START database provides a much more comprehensive list.

They are not tied to maps and interactive pattern analysis, and again reveal a lack of any consistent assessment of targets and motives involved, and of key factors like the ethnicity and sect of the target. This may have some degree of “political correctness,” but it severely limits the value of the data.

ISIS in Syria and Iraq

The single chart in this section clearly illustrates the fact that labeling all ISIS activity as “terrorism” borders on the absurd – given its clear evolution into a major insurgent movement and efforts to create the equivalent of alternative governments or “protostates.”

Terrorism in the West: Pre-Paris

These charts and trend data are supported by many similar analyses that show that the threat by violent Islamist movements to the United States, Europe, and other states with limited Islamic populations is all too real, but is marginal compared to the levels of violence that violent Islamist movements pose to fellow Muslims. It is also clear that the threat posed by non-Muslim local extremists has historically been as—or more—serious in the United States and other states with limited Islamic populations.

The events of 2015 have raised the level of violent Islamist attacks outside the Islamic world, but they have also sharply raised the level of violence within it. Such attacks have also been largely marginal relative to the ongoing battle by violent Islamist extremists against the governments of Islamic states and moderate mainstream Muslims. There is no “clash between civilizations,” but there is a very real battle for civilization within key parts of the Islamic world.

Foreign Volunteers

While the Vision of Humanity and Wikipedia estimates are a partial exception, the BBC charts and tables in this section illustrate the dangers in estimates whose sources and methods border on guesstimates, fail to portray critical uncertainties, do not clearly show the date of the estimate, and present gross estimates of the total numbers involved with no estimate of background and training, how they are integrated into the forces involved, and the real world level of networking and international mobility involved.

Estimates of foreign volunteers present a further major challenge because they have come to be seen as a returning threat and key reason for restricting or preventing the movement of Muslims to the United States and Europe. Exaggerating the numbers involved serves the terrorist cause by increasing tension between Muslim and non-Muslim.

This is made far worse by new media that hype such estimates without noting how small the number of volunteers really is as a percent of the key population bases that are the key potential source of volunteers. Here the BBC chart putting this into perspective is a key effort to put the size of threat in perspective.

ISIS Terrorism in the U.S.

These charts and chronologies highlight the actual Islamist extremist threat in the United States. It is clear that there have been many more suspect actions and attempts than successful attacks, but the number still remains very limited and the potential real-world threat is generally low.

Hate Crimes in the U.S.

The FBI analysis in this section serves as a grim reminder that the number of hate crimes in the United States—some against Muslims—greatly exceeds the threat from violent Islamist extremism.

Cost of Homeland Defense in the U.S. and Overseas Contingency Operations (OCO) Spending Outside It

The final section provides an OMB estimate of the President’s request for FY2016 cost of Homeland Defense, and a Department of Defense table showing the request for OCO funds in FY2016. There are no official data showing the cost-benefits of such expenditures, but this is characteristic of most reporting on government expenditures.

OMB reports that the total actual cost of homeland defense was $42.98 billion in FY2014, and the request rose to $47.97 billion in FY2016. The request projected expenditures as rising to $49.22 billion by FY2020.

Some $36.37 billion of the FY2016 request (76%) went to “Spending to Prevent and Disrupt Terrorist Attacks.” A total of $26.98 billion (56%) helped protect critical infrastructure, and the $6.47 billion (13%) was reported to respond to and recover from incidents.

The charts show that the vast majority of the OCO money has gone to warfighting, although this has included the build-up of counterterrorism forces in partner countries and combat against non-state actors that are major sources of terrorism. A total of $2.1 billion of the $50.9 billion in total proposed OCO funding in FY2016 went to the Counterterrorism Partnerships Fund (CTPF), or only 4.1%.

Anthony H. Cordesman

Anthony H. Cordesman

Former Emeritus Chair in Strategy