U.S. officials say they have made progress in tightening immigration in the wake of the 2001 terrorist attacks. But congressional critics insist more needs to be done to keep country safe from terrorists.
The 19 hijackers involved in the September 11 attacks entered the United States legally, though some were carrying fraudulent documents. Since then, the government has instituted a much tougher screening program that uses the latest technology to determine who is trying to enter the country and why.
Recently, Homeland Security officials told Congress that they now fear al-Qaida operatives might try to enter the United States by illegally crossing the border with Mexico.
That concern was echoed by a number of lawmakers, including Republican Senator John McCain of Arizona, which shares a long border with Mexico.
"I am worried about our border," he says. "We have now hundreds of thousands, if not millions, of people who are crossing illegally every year. And we are now seeing a larger number of people crossing our southern border who are from countries of interest as opposed to just Latin American."
The so-called countries of interest mentioned by Senator McCain are nations suspected of harboring radical or terrorist groups.
The possibility of terrorists trying to enter the United States by legal or illegal means is now considered a growing threat to U.S. security.
The director of the Central Intelligence Agency, Porter Goss, shared his concern during a recent U.S. Senate hearing.
"I think that is a very serious problem and I think it is not just our southern border," he said. "It is any border and it is part of the debate we have to have in our country about how does a free, democratic, open society go about the business of protecting itself from people who want to do us damage, who are not willing to play by any rules of society. It is a very difficult question."
Security experts say the United States had made progress in securing its borders since the 9/11 attacks but that much more needs to be done.
Janice Kephart was a staff member on the independent commission that investigated the 9/11 attacks.
"We are all here today because September 11 taught us an invaluable lesson that border security is national security," she said. "Effective border security is perhaps our best hope of preventing another terrorist attack on American soil."
One of the biggest changes for immigrants was the creation of the US-VISIT program at ports of entry. The program uses inkless fingerprints to biometrically verify the identity of foreign visitors and match them against watch lists of suspected or known terrorists.
Elaine Dezenski helped to implement the program for the Department of Homeland Security.
"The Visit program is the largest daily-use biometric program in the world with 100,000 people processed every day and it is working. Since January of 2004, the U.S. has denied admission at ports of entry to more than 450 individuals based on biometric information alone," Ms. Dezenski says.
But Homeland Security officials acknowledge that other loopholes in the immigration system remain. For example, there is still no effective method of tracking visitors who overstay their visas, a source of concern for several members of Congress.
"My understanding is that roughly 40 percent of the illegal immigration in the United States now comes from people who have entered the country legally but have overstayed their visa," says Republican Senator John Cornyn of Texas. "And we have no means, that is zero means of identifying where those people are or actually making sure that they leave the country when their visa expires."
Immigration officials within the Department of Homeland Security say their ability to check on those who have overstayed their visas will improve over time.
But some critics of the new immigration regulations say the government has gone too far.
Muslim-American groups in particular have raised objections.
Talat Hamdani lost her son in the September 11 attack on the World Trade Center. She recently spoke at a news conference held by the Coordinating Council of Muslim Organizations in Washington.
"This is a country of refuge, right? We all came here [and were greeted] with open arms and America accepted us and our [America's] trust was betrayed [with the 9/11 attacks]," Mr. Hamdani said. "I understand that. I lost my son also. However, that does not mean we should take away the due process of other people."
Even policy-makers in Washington acknowledge that finding a happy medium between security and openness can be difficult.
Homeland Security Secretary Michael Chertoff recently told an audience in Washington that the government must continually balance the need for security with the realization that the United States remains a favored destination for immigrants from around the world.
"What defensive action cannot and must not mean is that we shut down, board up, wall in or become a fortress," Mr. Chertoff said. "Because what we are trying to protect and at the same time preserve is not only lives but our way of life. America is a dynamic country. Our strength as Americans is the sum of every generation that has ever been born in or emigrated to this great land."
The immigration debate is expected to intensify later this year in Congress. Lawmakers will consider several proposals aimed at cracking down on illegal immigration. At the same time, House and Senate members may also take up President Bush's proposal for a guest-worker program that would make it easier for some illegal immigrants to remain in the United States.