Foreigners entering the United States through airports and seaports began getting their fingerprints scanned and photographs taken Monday as part of a new U.S. initiative to protect the homeland from terrorists.

The Homeland Security Department (search ) ordered U.S. airports and seaports to fingerprint and photograph foreigners as part of US-VISIT (search), or U.S. Visitor and Immigrant Status Indicator Technology. The program will check an estimated 24 million foreigners each year traveling on tourist, business and student visas who enter through an airport or seaport.

The exceptions will be visitors from 27 countries -- mostly European nations -- whose citizens are allowed to come to the United States for up to 90 days without visas.

Different rules apply for Canada and Mexico. Canadians are allowed into the country simply by providing proof of citizenship. Mexicans can apply for a permit to travel in the United States for up to three days provided they stay within 25 miles of the border. If they want to stay longer or travel further, they must obtain a visa.

The goal is "to ensure our borders remain open to visitors but closed to terrorists," Homeland Security Secretary Tom Ridge (search) said while launching the program Monday at Hartsfield-Jackson Atlanta International Airport, the busiest passenger airport in the United States.

"US-VISIT will help secure our borders and speed the delivery of legitimate travelers at our airports and seaports across the country," Ridge said in launching the program. "We welcome visitors of every variety … unfortunately, some have sought to take advantage of our open arms and welcoming shores."

Other top federal officials will be at other airports across the nation to help draw attention to the new policy.

All 115 U.S. airports that handle international flights and 14 major seaports are covered by the program, under which Customs officials can instantly check an immigrant or visitor's criminal background.

"This is making it easier for legitimate travelers to get into the country," Ridge told Fox News on Monday. And "we need an accurate record of who's leaving."

He noted that 21 individuals have already been prevented from traveling -- people who, according to FBI criminal watch lists, have previous convictions of statutory rape and visa fraud, among other crimes.

Ridge said the next step in protecting the nation's borders is to include biometrics on passports and to utilize facial scans and fingerprints to boost security at other travel points. The federal government will collect biometric data on those arriving in and departing from the United States on a visa.

Customs and Border Protection officers will collect inkless digital fingerprints and digital photographs from travelers, which will be checked instantly against a national digital database for criminal backgrounds and any terrorist lists. The process will be repeated when the foreigners leave the country as an extra security measure and to ensure they complied with visa limitations.

"It's easy for travelers to use but hard for terrorists to avoid," Ridge said.

The program will focus on "at risk" travelers while speeding the process for others and enforcing current visa policies, Ridge said. In test runs, he added, US-VISIT has been "a resounding success."

Homeland Security spokesman Bill Strassberger said once screeners become proficient, the extra security will take only 10 to 15 seconds per person. Foreign travelers also will continue to pass through regular Customs points and answer questions.

Photographs will be used to help create a database for law enforcement. The travel data is supposed to be securely stored and made available only to authorized officials on a need-to-know basis.

A similar program is to be installed at 50 land border crossings by the end of next year, Strassberger said.

Anticipating potential privacy concerns that may arise, Ridge said US-VISIT will be governed by federal privacy law and noted that the program actually protects visitors from identity theft and loss and theft of travel documents.

But US-VISIT "will not be kind to those who think that privacy can hide their hate or intention to harm," Ridge warned.

Brazilian police started fingerprinting and photographing Americans arriving at Sao Paulo's airport last week in response to the new U.S. regulations.

Brazil's Foreign Ministry has requested that Brazilians be removed from the U.S. list.

"At first, most of the Americans were angered at having to go through all this, but they were usually more understanding once they learned that Brazilians are subjected to the same treatment in the U.S.," Wagner Castilho, press officer for the federal police in Sao Paulo, said of those arriving at Sao Paulo-Guarulhos International Airport last Thursday.

The U.S. system consists of a small box that digitally scans fingerprints and a spherical computer camera that snaps pictures.

The new system will gradually phase out a paper-based system that Congress mandated be modernized following the Sept. 11, 2001, terrorist attacks.

A person whose fingerprints or photos raise questions will not be turned away automatically. The visa holder will be sent to secondary inspection for further questions and checks. Officials have said false hits on the system have been less than 0.1 percent in trial runs.

The system was scheduled to begin operation Jan. 1, but was delayed to avoid the busy holiday travel period.

Congress provided $368 million to produce the system and put it in airports, but only provided $330 million of the $400 million President Bush requested to put the system in land borders in 2004.

The Associated Press contributed to this report.