May 8, 2019 5:03PM

New Research on Immigration, Terrorism, and Ideology

Yesterday, Cato released my latest policy analysis entitled “Terrorists by Immigration Status and Nationality: A Risk Analysis, 1975-2017.”  Much of it is an update and expansion of my original policy analysis on this topic from 2016.  I added two more years of data, estimates of the number of people injured, and a handful of non-deadly foreign-born terrorists whom I had failed to include in my original paper.  The annual risk of being murdered in an attack committed by a foreign-born terrorist by visa category is very similar to my original study as there were only a handful of victims from attacks perpetrated by foreign-born terrorists in 2016 and 2017. 

Overall, the chance of being murdered by a foreign-born terrorist was about 1 in 3.8 million per year during the 43-year period in which 3,037 people were murdered.  Foreign-born terrorists who entered on tourist visas were the most deadly, responsible for over 96 percent of those deaths – largely because 18 out of the 19 9/11 hijackers entered on tourist visas.      

The changes to this analysis mentioned above are small, but there are two major additions that you should pay attention to.  The first is that I included all 788 native-born terrorists during this time by applying the same exclusion criteria that I applied to foreign-born terrorists.  It took years and reading tens of thousands of pages of government documents, news stories, dissertations, reports by non-profits, and more biographies of sketchy people than I care to remember.  Just for the record, there are a lot of Nazis who have been killed in shootouts with the police but most of them are not terrorists.  All 788 native-born terrorists are listed in the appendix.  If you think I missed somebody or included somebody I shouldn’t have, please let me know. 

The second major addition to the updated policy analysis is that I categorized all terrorists by the ideology that motivated them.  In order of the size of their body counts, the ideologies are Islamism, Right, White Supremacy, Left, Black Nationalism, Anti-abortion, Unknown/Other, Foreign Nationalism (Armenian terrorists targeting Turks in revenge for the genocide), Separatists (Puerto Rican independence, Texas secessionists, etc.), Anti-specific Religion (anti-Semitic shooters, etc.), Political Assassination, and Religious (non-Islamist).

I decided to separate White Supremacists, Right, and Anti-Abortion terrorists because they are all different ideologies.  True, they would mostly all label themselves as right-wing, but this enhanced level of detail conveys a deeper understanding of American terrorism.  Most Black Nationalists, Left, and Separatist terrorists would also label themselves as left-wing, but I made the same judgment call and separated them into their sub-ideologies for the same reason.  Similarly, separating Islamist terrorists into Sunnis or Shiites wouldn’t add much clarity so I didn’t do that.    

After the Christchurch mosque terrorist attack in New Zealand in March, many people wrote that right-wing or white-supremacist terrorism is on the rise.  While my updated report only covers the United States through 2017 and most of those writers were discussing the issue globally, my research can provide some evidence of whether this is true inside of the United States.

Over the entire 43-year period, the deadliness of Islamist terrorism dwarfs Right, White Supremacy, and Anti-abortion terrorism by factors of 16, 40, and 239, respectively.  The picture changes somewhat more recently as Islamists are responsible for 58 percent of all murders in terrorist attacks since 9/11, White Supremacists are responsible for 17 percent, Right terrorists for 10 percent, Left terrorists for 8 percent, and then the numbers get tiny.  Islamism is still the deadliest terrorist ideology in the post-9/11 world relative to Right, White Supremacy, and Anti-abortion, but by smaller factors of 6, 3, and 27, respectively.  Those numbers may well have diverged in 2018 and 2019, but I doubt they’ve changed enough to alter the general pattern.

Since 9/11, 184 people have been murdered by 378 terrorists in attacks on U.S. soil.  Of those 378 attackers, 62 managed to murder at least one person in an attack.  That means that only 16.4 percent of attackers succeeded in murdering somebody.  On this count, Right and White Supremacist terrorists are the most likely to succeed in murdering at least one person in their attacks at 28 and 22 percent, respectively.  Islamist terrorists have been less successful, with only 9 percent of them succeeding in murdering at least one person.  However, because there were so many Islamist terrorists and each one of them was deadlier on average, that ideology still inspires the deadliest terrorists.  It’s a bit premature to write the epitaph for Islamist terrorism in the United States.     

The main lesson from this report is that there are very few terrorists of any ideology or origin and even fewer who manage to murder Americans.  The 3,518 total murder victims of terrorism killed by foreign-born, native-born, and unknown terrorists from 1975-2017 account for only about 0.4 percent of the roughly 800,000 homicides during that time.  The ideology, frequency, deadliness, and origins of terrorists are fascinating but these numbers are so small that it is difficult to tease out any trend, let alone to be overwhelmed by fear. 

December 17, 2018 5:09PM

45,000 “Special Interest Aliens” Caught Since 2007, But No U.S. Terrorist Attacks from Illegal Border Crossers

President Trump claimed last week that “people are pouring into our country, including terrorists.” This came after his unsubstantiated claim that Middle Easterners are traveling in the caravan. Center for Immigration Studies (CIS) fellow Todd Bensman has repeatedly defended these types of claims by equating immigrants from “countries of interest” with “terrorists.” This conflation is common and rarely challenged as Homeland Security officials and members of Congress frequently describe immigrants from these countries as a terrorist threat. Despite Border Patrol apprehending tens of thousands of foreign nationals from these countries of interest and many thousands more who have undoubtedly entered illegally, not a single person has been killed by a terrorist who entered as an illegal border crosser from any of the countries of interest.

Special Interest Alien Apprehensions

The terminology used to describe these immigrants varies considerably between sources. In 2011, the Department of Homeland Security (DHS) Inspector General defined the term “specially designated countries” to mean countries “that have shown a tendency to promote, produce, or protect terrorist organizations or their members.” Border Patrol Chief David Aguilar described “Special interest countries” as “basically countries designated by our intelligence community as countries that could export individuals that could bring harm to our country in the way of terrorism.”

These definitions could apply to nearly every country in the world, as just about every major country has “produced” or “exported” at least one terrorist. With several exceptions, the lists have consisted primarily of countries with large Muslim populations. The designated countries have changed repeatedly over the years:

In 2003, DHS released a list of 52 countries. In 2004, the list included 35 countries, two of which were new. In 2007, the list was referenced in a news article, and though the full list was not quoted, it included another country (Tanzania) that was not on either of the prior two lists. In 2018, DHS released yet another list of countries where CBP “had Enforcement Actions against aliens from the following ‘Special Interest Aliens’ countries for FY18.” This partial list included yet five more countries that were not on the prior lists. Altogether, these lists have contained 63 countries. Only 14 have shown up on all the lists.

From 2007 to 2017, Border Patrol apprehended 45,006 immigrants from any of the countries ever designated as a “country of interest” (See Table 1). During the same period, it apprehended 4,109 from countries that made it onto all three lists. Given the inconsistency in these lists and for sake of completeness, Figure 1 shows the annual number of special interest aliens apprehended by Border Patrol separated by the different lists and those apprehended from countries that appeared at least once on a single list.  Fiscal Year 2007 is the earliest year that Border Patrol has made the number of apprehensions by citizenship publicly available.

Figure 2 shows that only 0.85 percent of all Border Patrol apprehensions from 2007-2017 were special interest aliens.  This includes aliens from any country that ever appeared on any special interest countries list.  The other 99.15 percent, 5.25 million apprehensions, were for illegal immigrants from countries other than those that have ever appeared on a special interest countries list.

With 16,979 apprehensions, Indians were the most common “special interest aliens” apprehended from 2007 to 2017, followed by Brazilians with 12,925 apprehensions. Both countries were on the 2003 list, but not listed in 2004 or 2018. Bangladeshis were the most commonly apprehended “special interest aliens” who were on all three lists with 2,469 apprehensions.

No Terror Attacks on U.S. Soil

Zero people were murdered or injured in terror attacks committed on U.S. soil by special interest aliens who entered illegally from 1975 through the end of 2017.  However, seven special interest aliens who initially entered illegally have been convicted of planning a terrorist attack on U.S. soil.  They all entered illegally from Canada or jumped ship in American ports before the list of special interest countries even existed.  None of them successfully carried out their attacks and none illegally crossed the Mexican border.

Five of those seven illegal border crossers resided as illegal immigrants in the United States.  Walid Kabbani, a native of Lebanon, walked across the Canadian border illegally in 1987 to deliver a bomb to his co-conspirators in the United States.  He was discovered by a local police chief and arrested before he could carry out his attack.  Algerian-born Ahmed Ressam attempted to enter with false documents in 1999 on his way to attack Los Angeles International Airport as part of the so-called Millennium Plot.  U.S. border inspectors apprehended him, discovered his bomb in the spare tire well of his car, and then arrested him.  In the scuffle to detain Ressam, he broke free of U.S. law enforcement officers and ran into the United States before being apprehended a short time later.  Since Ressam technically entered the country unlawfully when crossing the Canadian border, we included him on this list. 

Algerian-born Abdelghani Meskini aided Ressam in his plot after he entered the United States illegally as a stowaway on a ship.  Palestinian Gazi Ibrahim Abu Mezer, who was born in Israel and traveled on Israeli papers, was apprehended at a bus stop after illegally entering the United States in 1997.  Somali-born Nuradin M. Abdi originally entered the U.S. unlawfully in 1995 on a fake passport.  While he did not cross the border unlawfully, he did so on a false passport and would have been blocked like Ressam was if his subterfuge was discovered by Customs agents.  In order to include the maximum number of possible terrorists so that we bias the results against ourselves, we included Abdi.    

From 1975 through 2017, a total of nine terrorists entered the United States illegally and only three did so along the Mexican border: Shain Duka, Britan Duka, and Eljvir Duka.*  They crossed as children with their parents in 1984 and were arrested as part of the planned Fort Dix terror attack that the FBI foiled in 2007.  The Dukas are ethnic Albanians from Macedonia – neither country has appeared on any special interest countries list.  The only terrorists who crossed the border with Mexico illegally did so as children, decades before becoming terrorists, and were not even from the special interest countries.

In addition to the five illegal immigrant border crossers from the special interest countries, two people from those countries entered illegally and applied for asylum.  We typically count these people as asylum seekers, but Bensman and others might include them as illegal border crossers.  As a result, we decided to include them here.  Although data is a little sketchy on these instances, Pakistan-born Majid Shoukat Khan and Shahawar Matin Siraj are two of the eleven asylum-seekers who probably initially entered illegally before asking for asylum.  They entered in 1996 and 1998, respectively.  They are both from a special interest country, neither of them committed an attack, neither injured or murdered anyone, and they both crossed the Canadian border.

Although there have been zero attacks committed by illegal border crossers from any of the special interest countries, foreign-born people who entered legally from those countries were responsible for 99.5 percent of all murders and 94.7 percent of all injuries committed by foreign-born terrorists on U.S. soil from 1975 through the end of 2017.  This isn’t surprising as the 9/11 terrorists are responsible for over 98 percent of all the murders and 87 percent of all of the injuries committed by foreign-born terrorists over this time.  Of the small number of foreign-born terrorists who committed attacks or were convicted of planning to do so on U.S. soil from 1975 through the end of 2017, the most successful strategy was to first enter legally.  There is no evidence that that pattern of activity has changed.     


So far, there have been zero people murdered or injured in terror attacks committed by illegal border crossers on U.S. soil.  This includes those who entered as illegal immigrants and those who entered illegally and then applied for asylum.  Only seven terrorists from special interest countries, all of whom entered prior to the government putting those countries on a list, even entered the U.S. illegally by crossing a land border.  Two of them were arrested within hours of doing so, two other received asylum, and none of them crossed the Mexican border. 

Our above evidence is based on past events.  The future could be different, but those who think that special interest aliens from these countries will enter illegally across the Mexican border and commit terrorist attacks here should present some compelling evidence before policymakers take them seriously.   

*Numbers based on a forthcoming updated Cato Institute policy analysis.

November 28, 2018 2:07PM

Center for Immigration Studies Shows a Very Small Threat from Terrorists Crossing the Mexican Border

Todd Bensman, the Senior National Security Fellow at the Center for Immigration Studies (CIS), wrote a recent report entitled “Have Terrorists Crossed Our Border?” in which he presents a list of  “15 suspected terrorists have been apprehended at the U.S.-Mexico border, or en route, since 2001.”  Bensman lists these 15 individuals, some of which don't have names, and describes their actions.  He writes that his research is based on publicly available information, so it is likely a “significant under-count” of the actual terrorists who entered.  Bensman also writes that “several reports that strongly indicated the crossing of additional migrant terrorism suspects were excluded from this list due to insufficient detail.” 

If the goal of this CIS report was to show how small the terrorist threat along the Mexican border is, then it succeeded marvelously.  None of the terrorists identified committed an attack on U.S. soil, were convicted of planning an attack on U.S. soil, or even charged with doing so.  They killed or injured zero people on U.S. soil in terrorist attacks.  The only actual terrorism conviction for this group is of conspiracy to materially aid a foreign terrorist organization.  However, one person who entered the United States on his way to Canada did commit an attack in Alberta where he injured five people. 

Six of the 15 people that Bensman identifies are unnamed, thus we cannot independently verify or check whether they belong on this list (Table 1).  Interestingly, much of the evidence for those six unnamed individuals comes from passing comments in news stories or a Texas Department of Public Safety (DPS) report whose evidence is “deemed credible,” but that “could not be independently corroborated.”  Who deemed that evidence to be credible?  If people can’t independently corroborate the evidence, how can we know that it is credible?  We should take such claims with a large grain of salt, especially after frequent government terrorism exaggerations

Table 1 organizes the names that Bensman provides.  None committed or attempted to commit an attack on U.S. soil.  Two of the individuals were charged with terrorism offenses.  Mahmoud Kourani was charged and convicted of conspiracy to materially support a foreign terrorist organization (MSFT), Hezbollah, and sentenced to 54 months.  His actions are certainly troubling and should be illegal, but there is no evidence that he was a threat to American lives or property.  The Muhammad Kourani case is more nuanced and odd. He was a member of Hezbollah who became an informant for the United States.  After giving the FBI information on Hezbollah, the government used that information to charge Kourani with MSFT and conspiracy to do so.  There’s no evidence that he had any intention to every commit an attack on U.S. soil.  His trial will occur in 2019, so it’s premature to count him as a terrorist although he seems to have deep “ties” with Hezbollah.

Table 1
Terrorists, Suspected Terrorists, and Those with Suspected Terrorism Ties

Name Committed an Attack on US Soil Attempted or Planned an Attack on US Soil Terrorism Charges in the United States Terrorism Convictions in the United States Notes
Abdulahi Sharif No No No No Sharif committed an attack in Canada, injuring 5.
Ibrahim Qoordheen No No No No  
Unidentified Afghan national No No No No  
Muhammad Azeem No No No No  
Mukhtar Ahmad No No No No  
Unnamed Somali national No No No No  
Unnamed Sri Lankan national No No No No  
Unnamed Somali national No No No No  
Unnamed Bangladeshi National No No No No  
Abdullahi Omar Fidse No No No No 18 USC 1505 is not a terrorism statute, but there is an extra penalty if it involves a terrorism investigation. 
Mohammad Ahmad Dhakane No No No No  
Farida Goolam Ahmed No No No No  
Muhammad Kourani No No MSFT and MSFT Conspiracy No A court case is scheduled for 2019.
Al-Manar Television employee No No No No  
Mahmoud Kourani No No MSFT Conspiracy Yes  


Source: “Have Terrorists Crossed Our Border?” by Todd Bensman. 

Another interesting example is Ibrahim Qoordheen (sometimes spelled Qoordheer), who was arrested in Costa Rica while supposedly on his way to the U.S. border.  There is almost no publicly available research on him after his arrest in March 2017.  Gustavo Mata, the Costa Rican Minister of Public Security, said they would extradite Qoordheen to the United States if the U.S. government provided any evidence of his terrorism ties beyond a hit in a government database.  There is no government press release announcing his extradition to the United States and no other evidence online of what happened to Qoordheen, but he certainly wasn’t charged or convicted with any terrorism offenses in the United States. 

The only example of a real terrorist who crossed the border with Mexico during this time was Abdulahi Sharif.  He injured five people in an attack in Canada in 2017 and is currently awaiting trial there.  The evidence is sketchy, but Sharif apparently tried to enter the United States through a port of entry in 2011 and was detained – as he should have been.  There’s no indication that he made an asylum claim.  Regardless, the U.S. government let him go because it could not deport him to Somalia and lost track of him as he applied for refugee or asylum status in Canada in early 2012.  Five years later, Sharif tried to murder five people in Alberta, Canada.  Six years passed from Sharif’s attempted entry to the United States in 2011 to his attack in Canada in 2017.  His weapons were a knife and a car.  It’s hard to believe that he was planning to commit an attack before going to Canada, but a perfect system that could predict the future would have stopped him.  It bears repeating that Sharif did not commit an attack on U.S. soil and did not plan to commit an attack here.

Furthermore, Bensman’s rhetoric is unreasonably alarming relative to the scale of the terrorist threat along the Mexican border.  The title of Bensman’s report is “Have Terrorists Crossed Our Border?”  Surely, that means he must be talking about only terrorists, right?  Nope.  The subtitle walks back the title: “An initial count of suspected terrorists encountered en route and at the U.S. Southwest Border Since 2001 [emphasis added].”  So, his report only covers suspected terrorists?  Nope.  Elsewhere in the document, Bensman writes that his report:

[P]rovides an initial accounting of publicly documented instances, between 2001 and November 2018, of some 15 migrants with credibly suspected or confirmed terrorism ties who were encountered at the southern border after smuggling through Latin America, or who were encountered while presumably en route [emphasis added].

Those with “credibly suspected or confirmed terrorism ties,” are quite a bit different from suspected terrorists and even more distantly related to real terrorists.  Lots of people have “ties” to terrorists that are not significant in any way.  For instance, those related to terrorists have “terrorism ties,” but that does not mean that the family members of terrorists are themselves, terrorists.  In other words, he’s counting just about everyone apprehended who has “terrorism ties” according to “credible” evidence that “could not be independently corroborated” in many cases.  To see how ludicrous this standard is, which is common in much of the terrorism literature, substitute in another crime such as robbery for “terrorism” and see how unremarkable these statements are.   

This is a common rhetorical trick in terrorism publications.  For instance, a government list of “627 terrorism-related” prosecutions revealed that 45 percent of them were only convicted of non-terrorism offenses.  The three Abuali brothers are my favorites.  They are included in the government’s list of “terrorism-related” convictions even though their crime was stealing boxes of breakfast cereal, Kellogg’s specifically.  Stealing boxes of Raisin Bran is a crime, but depriving people of their breakfast doesn’t count as terrorism and neither are the cases that Bensman provides below. 

A count of real terrorists who have crossed the Mexican border since 2001 and wanted to harm Americans would be very short: it would contain zero names.  Three people entered the U.S. illegally through the Mexican border in 1984 and grew up to be terrorists who were convicted of planning an incompetent plot in 2008.  When Americans think of terrorists, they think of people attacking Americans on U.S. soil.  Sending information to Hezbollah is a terrorist offense and it should be illegal, but it is not as dangerous or severe as setting off a bomb or shooting people in pursuit of Jihad.  The only possible exception to this is Abdulahi Sharif who entered the United States on his way to Canada where he then committed an attack five years later. 

Bensman claims that he left out many names because of “insufficient detail,” but one can only imagine how thin the evidence against them is based on how little of it exists to condemn men with names as terrifying as “Al-Manar Television employee” and “Unnamed Bangladeshi national.”  Except for Abdulahi Sharif, who tried to enter through a port of entry and then went to Canada several years before committing his attack where he injured five people, there is little evidence of a terrorist threat from the Mexican border.  If this is the best evidence available of a terrorist threat across the Mexican border, then we should all feel a lot more secure.  

October 23, 2018 5:19PM

Does the Migrant Caravan Pose a Serious Terrorism Risk?

Yesterday, President Trump tweeted that “unknown Middle Easterners are mixed in” with the migrant caravan approaching the U.S. border. Vice President Pence later tried to justify President Trump’s comment by arguing that, “It is inconvincible that there are not people of Middle Eastern descent in a crowd of more than 7,000 people advancing toward our border.” Todd Bensman of the Center for Immigration Studies wrote that “the president was obviously referencing . . . ‘special interest aliens’ . . . U.S.-bound migrants moving along well-established Latin America smuggling routes from [Muslim] countries.” Perhaps President Trump was referencing special interest aliens but the clear implication is that they are potential terrorists who are using the caravan to sneak into the United States and murder Americans.  

The members of the migrant caravan will either apply for asylum at the U.S. border or try to enter illegally. From 1975 through the end of 2017, 9 Americans have been murdered in attacks committed on U.S. soil by 20 foreign-born terrorists who entered illegally or as asylees. During that time, the annual chance of being murdered in a terrorist attack committed by an asylum seeker or an illegal immigrant was about 1 in 1.3 billion per year. Those estimates are based on this methodology with updated numbers. 

During that time, about 31.3 million illegal immigrants entered the U.S. illegally (most have since emigrated, legalized, or passed away) and about 732 thousand asylum seekers have been admitted. Nine of the 20 terrorists who entered did so as illegal immigrants, meaning that about 1 terrorist entered hidden amongst every 3.48 million illegal immigrants. They killed zero people in domestic terror attacks. The 11 terrorists who entered as asylum seekers murdered 9 people in terrorist attacks or about 1 murder for every 81,000 asylum seekers let in.    

Of those 9 terrorists who entered illegally, only 3 did so along the border with Mexico: Shain Duka, Britan Duka, and Eljvir Duka crossed as children with their parents in 1984. They are ethnic Albanians from Macedonia. They were 3 conspirators in the incompetently planned Fort Dix plot that the FBI foiled in 2007, long after they became adults and more than two decades after they entered illegally. There is no evidence that the Fort Dix plot was more than 23 years in the making. 

As far as we can tell, virtually all the members of the migrant caravan come from Central America while the asylum-seeker and illegal immigrant terrorists who committed or attempted to commit attacks on U.S. soil came from Cuba, Lebanon, Pakistan, Palestine, Canada, Algeria, Somalia, Macedonia, Kyrgyzstan, and Afghanistan. Not a single terrorist in any visa category came from Mexico or Central America during the 43-year period.

None of the above estimates are meant to imply that those asylum seekers or illegal immigrants who committed or attempted to commit attacks were terrorists when they entered. Some, like Ramzi Yousef, obviously did enter as terrorists but the Boston Bombers Dzhokhar Tsarnaev and Tamerlan Tsarnaev entered as children too young to be plotting a terrorist attack years later. My colleague David Bier has shown just how rare it is that a foreign-born terrorist intends to come to the United States and how infrequently the government fails to stop him or her. 

This issue is complicated by the recent statements of Guatemalan president Jimmy Morales, who announced that his government “apprehended close to 100 persons completely involved with terrorists, with ISIS and we have not only detained them within our territory, but they have been deported to their country of origin.” Morales then stated that information about these supposed terrorists (like their names or countries of origin) was classified, which should raise a red flag as governments love to brag about their anti-terrorism actions with specifics even when such bragging is unjustified.

Even if we assume that some members of the migrant caravan are Middle Easterners who might pose a higher terrorism risk, that is still no good reason to bar the Central American migrants from applying for asylum. If some Middle Easterners are in this caravan, they too will be able to apply and face the same terrorism vetting procedures that work so well. There is little evidence that there are Middle Easterners in this caravan, even less that there are actual terrorists, and the risk from terrorists crossing the border has been tiny historically. This time could be different, but there is no real evidence to suggest that it is. Whatever problems may arise due to this caravan, the actual threat of terrorism from its members is very small.

August 15, 2018 4:06PM

The Chance of Being Murdered or Injured in a Terrorist Attack in the United Kingdom

On Tuesday, a Sudanese immigrant to the United Kingdom named Salih Khater crashed his car into cyclists and pedestrians in a terrorist attack in London. Fortunately, Khater did not murder anybody in his attack but he did injure three pedestrians, one of whom was so lightly wounded that he was treated at the scene and released. The other two wounded people have since been released from the hospital. 

Terrorism has been relatively common in the United Kingdom for decades, from the Irish Republican Army to al Qaeda to ISIS. However, there is little research on the actual risk of a British person being killed or injured in a terrorist attack. This post is an attempt to quantify that risk.

According to data from the Global Terrorism Database at the University of Maryland, the RAND Corporation, and online sources for 2018, terrorists murdered 2,402 people in the United Kingdom from 1975 through August 14, 2018 (Figure 1). Despite increases in the number of murders committed by terrorists in recent years, especially a series of horrible attacks in 2017 that murdered 42 people, the long run trend is a decline in the number of people murdered by terrorists in the United Kingdom. Figure 2 shows that 5,267 people were wounded in terrorist attacks in the United Kingdom during the same period. Figures 1 and 2 only include victims and exclude the terrorists themselves from the death and injury statistics. Using existing data sources, somebody with knowledge and a lot of time could use the GTD and RAND databases to identify the nativity, ideology, and other characteristics of each terrorist like I did for the United States

From 1975 through August 15, 2018, a British person’s chance of being murdered in a terrorist attack on British soil was about 1 in 1.1 million per year.  But that annual chance of being murdered in a terrorist attack obscures big shifts over time. Over the last decade, the annual chance of being murdered in a terrorist attack on British soil was about 1 in 11.4 million per year, far lower than the entire 1975-2018 period. Especially relevant is the number of injuries given that Khater only injured people in his attack. The annual chance of being injured over the entire time was 1 in 496,464 per year, but only 1 in 1.4 million per year over the last decade. 

Figure 3 tries to show how the risk has changed over time by using a moving three-year average of the annual chance of being murdered in a terrorist attack. I used a three-year moving average because zero people were killed by terrorists in many years and one cannot divide by zero. A note about reading Figures 3 and 4: the Y-axis is the annual chance of being murdered or injured in a terrorist attack, so the 2011 number of 63,280,444 in Figure 3 means that the chance of a British person being murdered in a terrorist attack was 1 in 63,280,444 that year. Thus, the higher the number, the lower the chance of being murdered in a terrorist attack. 

Figure 3 shows that the annual chance of being murdered in a terrorist attack fell rapidly from 1975 through 2004, rose over the next several years, fell again, and has been increasing since about 2012. Dropping the moving gives sharper divides: In 2016, 2017, and 2018 (so far), the annual chance of being murdered in a terrorist attack was about 1 in 7.3 million per year, 1 in 1.8 million per year, and zero (so far), respectively. 

Figure 4 shows a similar decline in injuries inflicted by terrorists from 1975 through 2003 that abruptly reverses in 2004, falls again in the following years, and then starts to increase over the last few years. 

These above figures show that the chance of dying or being injured in a terrorist attack in the United Kingdom is small. Yet terrorism succeeds in terrifying people. None of the numbers above would give comfort to the actual victims of terrorism or their families because what happened to them is the equivalent of “winning” an evil anti-lottery. But the above numbers should show British citizens, their government, and the world at large that terrorism is a relatively small problem in the United Kingdom.    

May 25, 2018 11:12AM

Counterterrorism Spending

The Stimson Center’s new study group report found that the federal government spent about $2.8 trillion on counterterrorism (CT) activities since 9/11.  The report seeks to account for all federal government spending on CT efforts divided into the four broad categories of defense emergency and overseas contingency operations, war-related state/USAID, other foreign aid, and government-wide Homeland Security.  The defense emergency and overseas contingency operations spending category accounts for about $1.7 trillion or over 60 percent of the $2.8 trillion spent.  War-related state/USAID and other foreign aid account for a relatively small $138 billion and $12 billion, respectively.  Government-wide Homeland Security spending makes up the rest at $978.5 billion since 9/11.

The big question the report does not attempt to answer is: Was all that spending worth it?  Did that spending result in fewer people killed by terrorists on U.S. soil?  One of the distinguished study group members is my Cato Institute colleague John Mueller who has spilled much ink trying to estimate the effectiveness of CT spending.  Mueller provides some back of the envelope estimates to answer the question of whether this CT spending was worth it in his recent panel discussion on the Stimson Center’s report.  After talking with Mueller, I decided to add some more analysis to show that an unreasonably large number of American lives would have to have been saved for the costs of CT spending to be justified.

For the costs of CT spending to equal the benefits in terms of the value of lives saved, it would have to have saved 188,740 lives, or 11,796 lives per year, since 9/11.  Narrowing down to just domestic CT spending on government-wide Homeland Security projects shows that spending on just that set of subprograms would have to have prevented the murder of 65,233 people, or 4,077 per year, to break even.  From 2002 through 2017, my latest estimate is that 172 total people were murdered on U.S. soil by all terrorists (Islamic, non-Islamic, domestic, U.S.-born, foreign-born, white supremacists, etc.).  Thus, all CT spending would have to have saved 1,097 times as many lives as were actually taken by terrorists in attacks on U.S. soil for the costs of CT spending to equal the benefits in terms of lives saved.  Focusing on just government-wide Homeland Security CT spending shows that it would have to have saved 379 times as many lives as were actually killed in terrorist attacks on U.S. soil to break even.  It is difficult to estimate a counterfactual but it would take a very creative imagination to honestly believe that post-9/11 CT spending actually saved that many lives by preventing terrorist attacks.


The first step is estimating the value of a statistical human life to compare with the cost of CT spending.  This is an emotional and fraught way to measure human life.  As a father and a husband, I understand this emotional reaction very well but the fact remains that if the government spends more than the statistical value of life to save a life through enhanced CT, then that means that other people died because of neglected safety in other areas.  As a hypothetical example, suppose the value of a statistical life is $15 million.  If the government spends $30 million to save one life by spending on X then that means that one person, at least, died who did not have to if that money was spent where it would save more lives.  Thus, spending that amount of money on reducing the risk of X results in more deaths than otherwise would have occurred.  Although emotional and hard to calculate, estimating the statistical value of life can help policymakers save more lives.  The death of human beings is the largest and most significant cost of terrorism but not the only one as other forms of destruction are also costly but relatively minor compared to death.  For the purposes of simplicity, I will focus on the cost in terms of human life.   

As I wrote in 2016, the Department of Homeland Security (DHS) produced an initial estimate that valued each life saved from an act of terrorism at $6.5 million, then doubled that value (for unclear reasons) to $13 million per life saved.  Adjusting for inflation raises that estimate to about $7.5 million.  Hahn, Lutter, and Viscusi use data from everyday risk-reduction choices made by the American public to estimate that the value of a statistical life is $15 million.  I use $15 million in this blog post as it is the largest number.

The second step is dividing the value of CT spending by the statistical value of life estimate to see how many lives would have to have been saved for that spending to equal the benefits.  I copy this method directly from Chasing Ghosts by John Mueller and Mark Stewart and their other important work on this topic

The third step is comparing the above results to the number of people who were actually murdered on U.S. soil in terrorist attacks.  Using the same methods as this policy analysis and including native-born attackers reveals that there were 172 people murdered in terrorist attacks on U.S. soil from 2002 through 2017.  That includes people murdered by terrorists of every ideology including Islamists, white supremacists, environmental extremists, and others regardless of where they were born.  


The first column in Table 1 shows that 188,740 lives would have to have been saved by all CT spending for the value of that spending to save an equivalent value in terms of human life.  The second column of Table 1 focuses on domestic Homeland Security CT spending, a subset of all CT spending, as it is most directly related to saving lives on U.S. soil.  To break even, domestic CT spending on Homeland Security would have to have saved 65,233 lives from 2002 through 2017 to break even (Table 1).    


Table 1

Number of Lives Saved for Counterterrorism Spending to Break Even


All CT Spending

Homeland Security CT Spending

Spending $2,831,100,000,000 $978,500,000,000
Statistical Value of Human Life $15,000,000 $15,000,000
Lives Saved to Break Even 188,740 65,233
Actual Terrorist Murders 172 172

Source: Author’s calculations.

If you assume that the value of statistical lives saved is equal to the cost of all CT spending, then you must also assume that all CT spending prevented at least 99.9 percent of all deaths that would have occurred in terrorist attacks on U.S. soil after 9/11 that were prevented.  If you just focus on domestic Homeland Security spending during that time and assume that the value of statistical lives saved is equal to the cost of CT spending, then you must assume that it prevented at least 99.7 percent of all deaths that would have occurred as a result of terrorist attacks on U.S. soil that were prevented. 

To put those numbers in context, about 250,000 Americans were murdered in non-terror homicides during that time.  There would have to have been about 1.4 murders in non-terror homicides for each person killed in a terrorist attack on U.S. soil for the cost of all CT spending to equal the value of human life saved in prevented attacks.  For only Homeland Security spending, there would have to have been about 2.9 murders in non-terror homicides for each person killed in a terrorist attack on U.S. soil for the cost to break even.  Does anyone believe that CT spending saved that many lives? 

Other Costs

The new Stimson Center study group report is a marvelous attempt to measure the nearly impossible-to-gauge extent of federal CT spending after 9/11.  Although the report is a good estimate of the direct amount of federal spending on CT, it does not represent the full cost.  Here are just a few additional costs that would have to be included to estimate such a number: 

  • State and local government CT spending.
  • The lost economic activity that would have occurred without expensive CT regulations.
  • The opportunity cost of this spending, including tax cuts or deficit reduction (the report hints at this as it mentions the death toll from opioids).
  • The trade and immigration restrictions promulgated after 9/11. 
  • The American military casualties in the War on Terrorism.
  • The foreign casualties in the War on Terrorism.
  • The increased numbers of deaths from consumers choosing riskier forms of travel rather than submit to the expensive, burdensome, and annoying demands of the TSA at airports.
  • Deaths that could have been prevented by redirecting CT spending toward other safety-enhancing policies.


The new Stimson Center study group report found that the cost of CT spending is gargantuan.  The cost of a government program is only one metric necessary to gauge whether it should exist as we must also consider the benefits it produces.  The number of lives that would have to have been saved for the cost of CT spending to equal the benefits, whether overall or just on Homeland Security, would have to be outrageously and unreasonably high for this expenditure to make sense.  By diverting government resources from other areas that would have boosted safety, even under the most negative conditions where the marginal cost saved is equal to the statistical value of life, assumes that hundreds of thousands of Americans died because of this increased CT spending who otherwise would have lived due to improved safety elsewhere.   










May 18, 2018 1:52PM

ICE Scraps Plans For “Extreme Vetting” Prediction Tech

Media Name: ice.jpg

During his presidential campaign Donald Trump proposed the "extreme vetting" of immigrants. Civil libertarians criticized the proposal, not least because the Extreme Vetting Initiative mandated by one of President Trump's first executive orders sought technology that would use machine learning to determine whether visa applicants would be likely to contribute to society and the national interest. Fortunately, Immigration and Customs Enforcement (ICE) – is no longer pursuing this vetting technology.

In January 2017 President Trump issued Executive Order 13769, which stated in part (emphasis mine):

Sec. 4. Implementing Uniform Screening Standards for All Immigration Programs. (a) The Secretary of State, the Secretary of Homeland Security, the Director of National Intelligence, and the Director of the Federal Bureau of Investigation shall implement a program, as part of the adjudication process for immigration benefits, to identify individuals seeking to enter the United States on a fraudulent basis with the intent to cause harm, or who are at risk of causing harm subsequent to their admission. This program will include the development of a uniform screening standard and procedure, such as [...] a process to evaluate the applicant’s likelihood of becoming a positively contributing member of society and the applicant’s ability to make contributions to the national interest; and a mechanism to assess whether or not the applicant has the intent to commit criminal or terrorist acts after entering the United States.

The Extreme Vetting Initiative tasked with implementing (among things) this feature of Trump's executive order, included the following in its statement of objectives:

ICE must develop processes that determine and evaluate an applicant’s probability of becoming a positively contributing member of society as well as their ability to contribute to national interests in order to meet the EOs outlined by the President.

A background document on the initiative outlined requirements, including the exploitation of publicly available information found on blogs, social media, academic websites, and other online sources. The same backgrounder went on to state that the goal was for the initiative to generate 10,000 investigatory leads each year.

Earlier this year dozens of computer scientists, mathematicians, and engineers wrote a letter to then-Acting Secretary of Homeland Security Elaine Duke, outlining the numerous issued associated with the Extreme Vetting Initiative. As I noted in November last year, the letter highlighted that ICE's proposal would likely be discriminatory as well as unreliable. From the letter:

According to its Statement of Objectives, the Extreme Vetting Initiative seeks to make “determinations via automation” about whether an individual will become a “positively contributing member of society” and will “contribute to the national interests.” As far as we are aware, neither the federal government nor anyone else has defined, much less attempted to quantify, these characteristics. Algorithms designed to predict these undefined qualities could be used to arbitrarily flag groups of immigrants under a veneer of objectivity.

Inevitably, because these characteristics are difficult (if not impossible) to define and measure, any algorithm will depend on “proxies” that are more easily observed and may bear little or no relationship to the characteristics of interest. For example, developers could stipulate that a Facebook post criticizing U.S. foreign policy would identify a visa applicant as a threat to national interests. They could also treat income as a proxy for a person’s contributions to society, despite the fact that financial compensation fails to adequately capture people’s roles in their communities or the economy.

For more information on the Extreme Vetting Initiative, including original ICE documents, visit the Brennan Center for Justice's resource page.