Yesterday, Cato published my policy analysis entitled “Terrorism and Immigration: A Risk Analysis” where I, among other things, attempt to quantify the terrorist threat from immigrants by visa category. 

One of the best questions I received about it came from Daniel Griswold, the Senior Research Fellow and Co-Director of the Program on the American Economy and Globalization at the Mercatus Center. Full disclosure: Dan used to run Cato’s immigration and trade department and he’s been a mentor to me. Dan asked me how many of the ten illegal immigrant terrorists I identified crossed the Mexican border?

I didn’t have a good answer for Dan yesterday but now I do. 

Of the ten terrorists who entered the country illegally, three did so across the border with Mexico. Shain Duka, Britan Duka, and Eljvir Duka are ethnic Albanians from Macedonia who illegally crossed the border with Mexico as children with their parents in 1984. They were three conspirators in the incompetently planned Fort Dix plot that was foiled by the FBI in 2007, long after they became adults. They became terrorists at some point after immigrating here illegally. Nobody was killed in their failed attack.

Gazi Ibrahim Abu Mezer, Ahmed Ressam, and Ahmed Ajaj entered illegally or tried to do so along the Canadian border. Ajaj participated in the 1993 World Trade Center bombing, so I counted him as responsible for one murder in a terrorist attack. Abdel Hakim Tizegha and Abdelghani Meskini both entered illegally as stowaways on a ship from Algeria. Shahawar Matin Siraj and Patrick Abraham entered as illegal immigrants but it’s unclear where or how they did so.

Based on this history, it’s fair to say that the risk of terrorists crossing the Southwest border illegally is minuscule.