How Have Terrorists Entered the U.S.?

By CIS on May 19, 2002

Contact: Steven A. Camarota
(202) 466-8185
[email protected]

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WASHINGTON A new study from the Center for Immigration Studies examines how foreign terrorists entered and remained in the country over the past decade. To provide a more complete picture of the threat, the report examines the immigration status not only of the September 11 hijackers but of all 48 foreign-born, radical Muslim terrorists, almost all of them linked to al Qaeda, who have been charged, convicted, or admitted involvement in terrorism in the United States since 1993.

The report, entitled "The Open Door: How Militant Islamic Terrorists Entered and Remained in the United States, 1993-2001," by the Center's Director of Research Steven A. Camarota, contains immigration histories for each of the 48 terrorists. Contrary to claims that foreign terrorists have come only as temporary visitors, research indicates that they have manipulated almost every possible means of admission to the United States: Some have indeed come as students, tourists, and business travelers; others, however, have been Lawful Permanent Residents and naturalized U.S. citizens; while yet others have snuck across the border, arrived as stowaways on ships, used false passports, been granted amnesty, or been applicants for asylum.

The report is on line at

Among the findings:

  • At the time they committed their crimes: 16 (one-third) of the 48 terrorists were on temporary visas (primarily tourists); 17 (another third) were Lawful Permanent Residents or naturalized U.S. citizens; 12 (one-fourth) were illegal aliens; 3 of the 48 had applications for asylum pending.
  • Violations of immigration laws are very common among terrorists. Not only were 12 of the 48 terrorists illegal aliens when they committed their crimes, but at least ten others had significant violations of immigration law prior to taking part in terrorism.

"Because every part of our immigration system has been exploited by terrorists, we cannot reform just one area, but must address the problems that exist throughout," said Camarota. "The solution is not to single out Middle Easterners for exclusion or selective enforcement. Instead we need to more carefully check the backgrounds of all visa applicants, better police the borders, strictly enforce the law within the country, and, most important, reduce the level of immigration to give the INS the breathing space it needs to implement fundamental reforms."

Other findings:

  • Past amnesties for illegal aliens have facilitated terrorism. Mahmud Abouhalima, a leader of the 1993 World Trade Center bombing, was legalized as a seasonal agricultural worker as part of the 1986 amnesty, which allowed him to travel abroad, including several trips to Afghanistan, where he received terrorist training.
  • Several terrorists should probably have been denied temporary visas, because they had characteristics that made it likely they would overstay and live in the U.S. illegally. Under Section 214(b) of the Immigration and Nationality Act, individuals who are young, unmarried, unemployed, or lack strong attachment to a residence overseas are to be denied temporary visas. Several of the September 11th hijackers, including Mohammed Atta, fit these criteria.
  • Although the September 11th hijackers entered on temporary visas, legal immigrants and naturalized U.S. citizens have also played key roles in terrorism on U.S. soil. For example, Siddig Ibrahim Siddig Ali, ringleader of the plot to bomb New York City landmarks in 1993, is an LPR, and Ali Mohammed, who wrote al Qaeda's terrorist handbook, is a naturalized U.S. citizen.
  • In addition to overstaying visas, terrorists have engaged in fraudulent marriages to American citizens, such as Khalid Abu al Dahab, who raised money and helped recruit new members for al Qaeda. Others have provided false information on their applications for green cards, like Sheik Omar Abdel Rahman. And at least eight terrorists held jobs illegally.

POLICY RECOMMENDATIONS: While no security can be foolproof, if only some of those involved in a terrorist plot can be stopped by our immigration system, then it is possible that whatever conspiracy they are involved in will unravel, as was the case with the Millennium plot. Four general reforms are needed. First, improvements in how visas are processed overseas are needed, including more vigorous background checks and interviews for all visa applicants. Second, the fact that terrorists often flout the law means that strict enforcement of immigration law within the United States could reduce the terrorist threat. Third, there needs to be a significant increase in efforts to police the borders. Improving visa processing while leaving the borders largely undefended is an invitation for terrorists to do as attempted Brooklyn subway bomber Gazi Ibrahim Abu Mezer did; having been denied a visa, he simply went to Canada and snuck across the border.

The fourth reform that is needed is a reduction in overall immigration, both temporary and permanent. Given limited governmental resources, issuing fewer visas would mean that greater resources could be devoted to background checks on each applicant. It would also mean fewer people to keep track of within the country. Most important, it would give the State Department and Immigration and Naturalization Service the breathing space they need to deal with enormous processing backlogs, now close to 5 million applications, and allow them to undertake necessary reforms. It is simply not reasonable to expect any agency, and especially the INS, to deal with such huge backlogs and take on steadily proliferating responsibilities and at the same time fundamentally restructure itself.