The White House announced changes to the U.S. visa waiver program Monday that would allow security officials to more closely screen travelers from 38 countries whose citizens are currently allowed to enter the U.S. without obtaining visas. These new measures could force millions of travelers from countries like Britain to obtain updated travel documents if they want to enter the United States, the Telegraph reported.

The changes to the visa waiver program, which has been in place since 1988, are part of the U.S. Department of Homeland Security's response to the Nov. 13 terror attacks in Paris, Reuters reported. The updated security measures would allow DHS to collect more information about travelers’ previous visits to countries such as Syria and Iraq.

The measures will “enhance our ability to thwart terrorist attempts to travel on lost or stolen passports,” White House press secretary Josh Earnest told reporters in Paris, where President Barack Obama was attending a U.N. conference on climate change.

Other security updates include a pilot program that would allow the DHS to collect biometric information such as fingerprints from visa waiver travelers, the ability to require all travelers to use passports with security chips, and the authority to increase fines for airlines that do not verify passport data.

The Obama administration also wants to expand a “preclearance program” in foreign airports that would allow U.S. officials to screen visa waiver travelers before they board planes to the U.S. Earnest said Monday that the White House hopes Congress will pass legislation before it leaves for a holiday recess in December.

Under the new security measures, travelers from countries that have long participated in the visa waiver program may be required to obtain new passports if they do not have documents with biometric chips. In Britain, officials estimate that about 5 million of the country’s 50 million passport holders possess older travel documents that do not contain the necessary technology, the Telegraph reported. If they are forced to renew their passports earlier than otherwise necessary, that could cost at least  £72.50 per person ($109.44).

The microchips in British passports contain an electronic version of the owner’s photograph, as well as information including date and place of birth, nationality and gender. These microchips were introduced in Britain in 2006, and many other countries have also introduced similar technology.

U.S. House Majority Leader Kevin McCarthy, R-Calif., told reporters Monday that a task force would meet Tuesday and aim to pass legislation “by the end of the year.” He also said lawmakers were interested in requiring all countries in the visa waiver program to issue “e-passports” that include biometric chips, Reuters reported.

While many lawmakers and politicians have raised the alarm about potential terrorists sneaking into the United States with refugees from Syria and Iraq, Reuters reported that U.S. officials believe it is more likely for would-be terrorists to enter from visa waiver countries. The U.S. takes 18 to 24 months to screen Syrian refugees, whereas 20 million people travel by plane to the U.S. each year from countries such as Britain and France.

Officials are now worried that a European who has traveled to Syria to train with a terrorist group such as the Islamic State group could enter the U.S. without scrutiny if they were not already known to U.S. intelligence or its partners. Depending on the details of legislation passed in December, other countries may experience situations to those of Britian, whose citizens would need to upgrade or obtain new travel documents before entering the United States.