(March 2002) On Sept. 11, 2001, 19 men hijacked four planes over U.S. airspace and, using the planes as bombs, caused the deaths of more than 3,000 people. The hijackers apparently were foreigners who had been in the United States from a week to several years. At least 16 had entered with legal student or tourist visas.

In the wake of the attacks, the United States and many other countries are examining their immigration policies and considering ways to thwart potential terrorists. Immigration policy reforms cannot prevent terrorism, but they are a key part of any effort to combat terrorism. Immigration policies aim to facilitate the entry of wanted foreigners, and to identify and deter the entry of terrorists and other unwanted foreigners.

Policy Reform Challenges

The Sept. 11 terrorist attacks highlighted four reasons that current U.S. immigration policy does little to thwart international terrorists. First, the procedures for obtaining visas and identification documents do not deter potential criminals from entering the country. All the hijackers were able to obtain seemingly valid visas with supporting documents.

Second, illegal entry into the country is relatively easy, even without visas, because of the long and lightly guarded national border. In December 1999, Algerian Ahmed Ressam was caught attempting to enter the United States from Canada with bomb-making materials that he planned to use to bomb the Los Angeles International Airport during the millennium celebrations.

Third, the U.S. government does not track the movements of foreigners inside the country. For example, one of the Sept. 11 hijackers was admitted to the United States to study English, but he never showed up at the school that admitted him. There is no system to alert law enforcement of visa violations that might uncover a potential terrorist plot. Several of the hijackers were in the country with expired visas.

Fourth, there has been (until recently) little cooperation or information-sharing among countries about terrorist suspects.

There are three major areas in which changes in immigration policies may be able to counter future terrorist threats: visa issuance and entry inspections, border controls, and interior enforcement. The United States may also have to pay special attention to foreign students and consider harmonizing immigration and asylum policies with Canada to preserve a fairly open Canada-U.S. border.

Entries to the United States are screened through the National Automated Immigration Lookout System, or NAILS, which contains the names of foreigners believed to pose a security risk to the United States. But false names supported by fraudulent documentation can fool NAILS. An improved lookout database must be capable of matching not only names, which can be easily changed, but also biometrics such as fingerprints and facial characteristics. NAILS could be enlarged with information from the FBI.

Another way to tighten the borders is to track the entries and exits of all foreign visitors. The current system to record entries and exits — via the I-94 form — is not effective for tracking potential criminals. Entry-exit tracking was opposed by Canada and northern U.S. states because its cost and inconvenience would hurt commuting, trade, and tourism.

Technology could ease some of these drawbacks and make it easier to track foreigners in the country. Australia, for example, uses an electronic visa that is incorporated into the airline ticket, which could be a model for a similar U.S. program. The United States already is experimenting with commuter lanes on the Mexico-U.S. border that permit officials to screen regular travelers and issue them special documentation and devices for their cars to speed crossings without sacrificing security.

The U.S. Immigration and Naturalization Service (INS) stepped up border enforcement in the 1990s by adding agents, fences, and lights along the borders in urban areas in Arizona, California, and Texas. Expanding this strategy to more of the 2,000 mile Mexican-U.S. border would help to deter unauthorized migrants, including potential terrorists. But expanding border controls would cost more money and would take time to implement.

Surveillance of foreigners already in the United States is a controversial issue because many view it as an unacceptable police presence. After the Sept. 11 attacks, many U.S. universities dropped their long-standing opposition to the tracking of foreign students, but many Americans oppose the idea of a national identification system that would require all U.S. residents to carry a counterfeit-resistant ID. The current system makes it easy for unauthorized foreigners to get “legal” identification. Three of the Sept. 11 hijackers apparently got Virginia driver’s licenses using fraudulent documents.

International Cooperation

The United States and Canada could harmonize their immigration and asylum policies to erect a “security perimeter” around the two countries, following the European Union (EU) model. The Schengen Agreement permits freer movement within the EU because entry and exit controls are done at the external border of the 13 participating countries. Such a system could be feasible with Canada, and perhaps eventually with Mexico.

International cooperation can help prevent terrorism from slowing economic globalization. Cooperation and data sharing can help to identify suspected terrorists and prevent them from moving from one country to another to carry out attacks. Cooperation will also be needed to combat smuggling and trafficking operations that could be used by terrorist organizations to move persons clandestinely.

Terrorists pose a formidable challenge common to all countries. But tackling terrorism is likely to result in closer cooperation among the industrialized countries, and gradually to a convergence in their immigration and asylum policies.


Philip Martin is professor of agricultural economics at the University of California-Davis, chair of the University of California’s Comparative Immigration and Integration Program, and editor of Migration News.

Jonas Widgren is the director of the International Center for Migration Policy Development. 


Adapted from Philip Martin and Susan Martin, “Immigration and Terrorism: Policy Reform Challenges.” Paper prepared for a conference on immigration sponsored by the German Marshall Fund of the United States and the King Baudouin Foundation, Brussels, Oct. 14-15, 2001.


Excerpted from PRB’s Population Bulletin “International Migration: Facing the Challenge” (PDF: 379KB).