The U.S. Department of Homeland Security (DHS) is concerned that radical Islamists with European passports may exploit the U.S. "visa waiver" program to enter the United States.

This suggests that traditional U.S. mechanisms for controlling the influx of foreign visitors are inadequate in the post-Sept. 11, 2001, context. However, U.S. attempts to address this vulnerability would be economically costly and politically fraught.

In recent months, the DHS has expressed particular concerns about British Pakistanis, due to fears that some members of this community have been radicalized; such individuals often have no criminal records and are not on U.S. watch lists.

States usually accord the right to enter to enter with conditions, which include time limits on stay and a visa issued by that state. U.S. visa policy for tourists distinguishes between those with a visa requirement (people from countries with high emigration rates or that pose security risks), those for whom the visa is waived (mainly western European countries) and Canada (whose citizens now enter on the basis of a driving license or passport alone).

Visa holders are subject to a significantly greater level of scrutiny. Candidates have their application checked against watch lists, which usually include convicted criminals and those suspected of terrorist ties. Consular officers attempt to develop a behavioral profile based on the information they secure, which supposedly identifies high-risk subjects.

Additional information is solicited from nationals of states designated as "terrorist sponsors" by the State Department--North Korea, Cuba, Syria, Sudan and Iran--on the applicant's tribe or clan; affiliations with professional, social and charitable organizations; participation in military conflict and details of any military service; and specialized skills and training.

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