This section of DiscoverTheNetworks examines how a lack of immigration-law enforcement leads to a rise in the incidence of illegal border-crossing, which in turn makes it easier for aspiring terrorists to enter the United States.

The terrorist attacks of 9/11 should have put the issue of border security on the front burner not only of America’s immigration policies but of its ntional security policies as well. Even among Hispanics, a group thought to favor liberal immigration policies, a majority of 56% wanted "tougher immigration [controls] in light of security concerns," according to a national poll commissioned by a Hispanic business magazine in late 2003.

Each year since the mid-1980s, hundreds of thousands of illegal immigrants have simply walked across the U.S.-Mexican border and moved inland without interception. The United States has also experienced explosive growth in the number of foreigners admitted to the country on a "temporary" basis using "non-immigrant" visas—from 7 million admitted in 1980 to nearly 33 million in 2001. There is no specified limit to the number of non-immigrant visas that can be issued in any given year. Most go to tourists, visiting relatives, or business travelers who do return home. But many of these temporary immigrants overstay their visas and fade into the illegal alien population. About 40 percent of the estimated 12 to 20 million illegals presently living in the United States entered the country by this method. A number of the 9/11 terrorists fell intothis category.

In 2005 the Center for Immigration Studies published a report covering the immigration histories of 94 foreign-born terrorists -- including six of the 9/11 hijackers -- who had been active in the United States between the early 1990s and 2004. Among the findings:

• Of the 94 terrorists, about two-thirds (59) committed immigration fraud prior to, or in conjunction with, their terrorist activity.
• Of those 59, many were guilty of multiple immigration violations — 79 instances in all.
• In 47 of those instances, the transgressors were able to stay in the U.S. even after 9/11 -- thanks to immigration benefits they had sought or acquired prior to 9/11.
• Temporary visas were a common means by which the terrorists entered the United States: 18 had student visas; another 4 were approved to study in the U.S.; and at least 17 used visitor visas.
• There were 11 instances of passport fraud and 10 instances of visa fraud; in total, 34 individuals were charged with making false statements to immigration officials.
• In at least 13 instances, terrorists overstayed their temporary visas.
• In 17 cases, terrorists claimed to lack proper travel documents and applied for asylum, often at a port of entry.
• Seven terrorists were indicted for acquiring or using various forms of fake identification, including driver’s licenses, birth certificates, Social Security cards, and immigration arrival records.
• Once in the United States, 16 terrorists became legal permanent residents, in numerous cases by marrying Americans. There were at least 9 sham marriages among the 16.

The correlation between illegal immigration and terrorism was made explicitly clear in March 2006, when FBI Director Robert Mueller testified to Congress that his agency had recently dismantled a Hezbollah smuggling operation that was bringing terror personnel across the U.S. border from Mexico. Since the late 1980s, Hezbollah has created an extensive, sophisticated web of operations within the United States itself. According to Tom Diaz and Barbara Newman, co-authors of Lightning Out of Lebanon: Hezbollah Terrorists on American Soil, active Hezbollah cells have been positively identified in Boston, New York, Newark, Atlanta, Miami, Tampa, Charlotte, Louisville, Detroit, Cleveland, Chicago, Houston, Los Angeles, San Francisco, and Portland. Former FBI Hezbollah Unit director Bob Clifford has called Hezbollah "the best light infantry in the world," with the ability to "strike the United States anytime, anywhere."