The U.S. government has started asking some foreign visitors to provide their social media account information as part of the effort to identify potential terrorists. Since last week, foreigners arriving in the U.S. on the visa waiver program are asked to identify the social media platforms they use and their account names. Even though the request is optional and U.S. officials have said they would not deny entry to anyone who declines to disclose the information, the move has generated a backlash from civil rights groups and the tech industry. Groups such as the American Civil Liberties Union and the Center for Democracy and Technology have warned that the move could potentially offer the government "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." Critics also warn that the program could be used to target Arabs and Muslims and expose them to intense scrutiny. The Internet Association — a group that represents companies including Facebook, Twitter and Google — argues the new policy threatens free expression. Currently, visitors from 38 countries are able to use the visa waiver program that allows them to travel and stay in the United States for up to 90 days without a visa.