Washington (CNN) The U.S. began implementing changes Thursday to its visa policies that will make it harder for some Europeans to travel to the United States in a bid to keep ISIS adherents out of the country.
The new rules apply to European, Japanese and Australian travelers to the United States who have visited Iran, Iraq, Sudan or Syria since 2011 and dual-citizens who have citizenship in one of those countries.
Under the change, these individuals will no longer be able to enter the United States without applying for a travel visa.
Currently, the Visa Waiver Program allows citizens of participating countries to travel to the U.S. without obtaining a visa. Thirty-one of the 38 countries in the program are European nations, with some Asian countries included as well, according to the State Department.
The adjustment was mandated by legislation passed in the wake of November’s deadly ISIS-linked terrorist attacks in Paris, where several of the perpetrators were European citizens.
The House overwhelmingly passed the bill in December, with House Homeland Security Committee Chairman Michael McCaul, a Texas Republican, saying this month that the previous arrangement was a “huge security gap that needed to be fixed.”
The vast majority of foreign fighters who have joined ISIS or other terrorist groups and then returned to the West have gone to Iraq and Syria. Syria, Iran and Sudan are also designated as state sponsors of terrorism, according to the State Department.
While the new rules are unlikely to affect great numbers of people, in December the European Union Ambassador to the U.S., David O’Sullivan, along with 28 ambassadors from E.U. countries, wrote an op-ed in The Hill expressing some concerns about the change to the visa program.
He warned that a “blanket restriction” on those who have visited Syria or Iraq would likely affect those legitimately engaged in business, journalism and humanitarian work “while doing little to detect those who travel by more clandestine means overland.”
He added that dual citizens of E.U. countries and those states included in the new guidelines would also be “disproportionately and unfairly affected.”
An E.U. official told CNN Thursday, “We are following this closely and waiting to see what the impact on our citizens will be.”
The individuals affected by the new rules will still be able to apply for a visa using the regular immigration process at their respective embassies or consulates.
Under the new law, the secretary of Homeland Security may waive the restrictions for individuals whose entry is deemed to be in the national security interests of the United States.
According to the State Department, qualifying individuals could include government officials, representatives of non-governmental and international organization, journalists and people who traveled to Iraq or Iran for “legitimate business-related purposes.”
The addition of individuals who have traveled to Iran for business purposes has proven contentious on Capitol Hill, with Republicans in Congress blasting the move.