Citizens of 38 countries, including many in Europe, will face new restrictions on travel to the United States under changes to the "visa waiver" program tucked into a massive spending bill unveiled in the U.S. Congress on Wednesday.
U.S. officials have been eyeing the visa waiver program, which allows citizens of close allies to enter the country without being screened, since last month's Islamic State attacks in Paris.
Several of the attackers held European passports that would have allowed them to easily enter the United States under the existing system.