The Uncertain Trends and Metrics of Terrorism in 2016

By Anthony H. Cordesman with the assistance of Max Markusen

The global trends in terrorism present some of the most complex problems for analysis in U.S. national security. The Burke Chair at CSIS has updated a survey of such trends that highlights a wide range of developments since 1970, as well as more recent trends in 2015 and 2016. This analysis is entitled The Uncertain Trends in Terrorism and is available on the CSIS web site at The analysis includes both broad trends as presented in the U.S. State Department Country Reports on Terrorism and START data base, and key trend metrics from other sources and NGOs.

The report’s Table of Contents include:

The analysis provides a wide range of different metrics for measuring the patterns in global and regional terrorism, the impact of Islamic extremism, and how terrorism varies by region.

Drawing on the START Data Base

The analysis draws heavily on the START data base maintained by the University of Maryland and used by the State Department in its annual country reports on terrorism ( The START database is now the closest thing available to an official U.S. data base, and is the primary source of most U.S. media, research center, and academic estimates.

It also draws heavily on the work of the Institute for Economics and Peace (IEP) and its Global Terrorism Index 2016 ( The IEP also makes source use of START, but is a key source of independent estimates and narrative analyses, and makes independent assessments of the impact of terrorism and its economics.

A Lack of Leadership and Focus by the National Counterterrorism Center (NCTC)

Many of the broad trends presented in this study seem generally valid, and comparative views are presented where major differences exist between sources. However, no analysis can overcome the fact that all current unclassified estimates of terrorism suffer badly from the fact that the National Counterterrorism Center (NCTC) has lacked the leadership and focus to maintain its declassified data base on terrorism, and now provides no meaningful official transparency on the patterns in terrorism.

The START data base gets its source data from media reporting and has major gaps and uncertainties clearly recognized in the description of the database and its supporting analyses. It is particularly weak in the areas where governments fail to allow accurate reporting on terrorism in their media. Useful as the START data base and other independent analyses are, relying on public reporting leaves major problems and gaps in the data available.

The fact that the NCTC no longer reports numbers or patterns on an unclassified basis means there now is no official unclassified U.S. data reporting on the trends in terrorism. This lack of transparency means there is no source of that allows comparisons of official estimates with NGO and media sources, and no way to analyze the effectiveness of counterterrorism based on official estimates of its effects.

Only reporting that can draw on the releasable portions of the broader data bases within the U.S. government can provide the depth and accuracy of coverage needed to provide an accurate picture of all the key trends in terrorism and extremism and assess the effectiveness of official efforts. The NCTC’s decision to stop providing such data makes such analysis impossible.

Broader Problems in the Data and Reporting

Moreover, cataloguing the trends, methods of analysis, and data from the wide range of sources used in in this survey has revealed a much wider range of problems. It is clear there may be critical problems in the ways the U.S. government, other governments, and NGOs approach terrorism and counterterrorism:

  • The definition of “terrorism” used in many is not clearly stated, and it is often politicized.
  • Most sources do not show how they separate terrorism” from insurgency, internal conflicts, and low-intensity conflict. The rising level of such violence in the MENA and other regions is either treated as terrorism or not addressed.
  • Most sources do not attempt to estimate uncertainty, and many do not explain their 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 population.
  • As a result, virtually all terrorism and extremism reporting focuses on non-state actors.
  • Excessive repression in the name of counterterrorism -- and state activities that amount to de facto state terrorism -- are not reported as terrorism even when they clearly have such impacts. These problems in the counterterrorism activity of various states – some U.S. partners and allies – are only officially reported – if at all -- in the State Department annual human rights report and reports by various human rights NGOs.
  • No clear source or method exists to estimate the impact of terrorism in creating refugees, internally displaced persons, lasting human and humanitarian impacts, collateral damage, and economic impacts.
  • Casualty data are highly uncertain. Most sources only attempt to count casualties caused by non-state actors. They often confuse terrorism with insurgency and internal power struggles, and many sources only address killed, rather than injured or wounded.
  • Incident counts and casualty data are also 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.
  • 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 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.
  • Most sources do not identify attackers, attacks, and targets by sect, ethnicity, and tribe.
  • Perpetrator data are often very uncertain, and vary sharply from source to source.
  • Both the identification of the perpetrators and the level of affiliation with given terrorist groups is often very uncertain, and many assessments do not attempt to deal explicitly with these uncertainties.
  • Most data are global or nationwide. It is generally difficult to trace the patterns within given parts of what often are deeply divided countries or movements that cross national borders.
  • 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, and on the overall patterns in extremism.
  • The actual date of many sources is not specified or unclear.
  • Aside from chronologies – whose content differs sharply from source to source – reporting – the nature of how terrorist attacks are being defined is often unclear.
  • Most sources seem to undercount countries where there is limited media reporting on any form of dissent. This lead to low figures for Central Asia and parts of East Asia, and suspiciously low totals for a large number of countries.
  • Scattered small attacks on various ethnic groups, sects, tribes, and minorities add up to major cumulative levels of violence and terrorism over time, but are not generally reported as terrorism unless some terrorist group claims responsibility and are catalogued as hate crimes. The end result is often massively undercount the actual level of violence by Islamist extremists, sectarian and ethnic fighters, and tribal violence.
  • 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 except in human rights reporting.
  • 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. counter terrorism effort – and its strength and weaknesses -- are provided by the Department of Homeland security, but these cover only a small part of part of the U.S. domestic effort, however, and do not cover overseas contingency operations. The basic focus of DHS effectiveness data is immigration and border/coastal security.*

* For 2015 examples, see, and

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