Foreigners coming into the U.S. are being requested to provide their Facebook, Twitter and other social media accounts upon arriving in the country, Politico reported Thursday.

The move is designed to detect potential terrorist threats.

Beginning Dec. 20, those arriving to the U.S. on the visa waiver program have been presented with an “optional” request to “enter information associated with your online presence,” a government official told Politico. The waiver program allows citizens of 38 countries to travel and stay in the U.S. for up to 90 days without a visa.

The request includes a drop-down menu when filling out the Electronic System for Travel Authorisation (ESTA). That section lists social sites like Facebook, Google+, Instagram, LinkedIn and YouTube, as well as a space for users to input their account information.

A spokesperson for Customs and Border Protection told Politico that the government approved the move on Dec. 19, and that the new policy is meant to “identify potential threats.” The agency had previously said those who did not provide their social media account information would not be prohibited to enter the country.

The move drew months of opposition from the tech industry and privacy leaders.  

In a letter sent over the summer, the ACLU, Center for Democracy and Technology said the policy posed vast privacy risks, since social media profiles serve as “gateways into an enormous amount of [users’] online expression and associations, which can reflect highly sensitive information about that person’s opinions, beliefs, identity and community,” according to Politico.

The organizations also said the policy would “fall hardest on Arab and Muslim communities, whose usernames, posts, contacts and social networks will be exposed to intense scrutiny.”