U.S. officials have quietly begun a new program asking noncitizen travelers to reveal their social media presence when entering the country. On Tuesday, U.S. Customs and Border Protection started providing foreigners on the visa waiver program with a computerized drop-down menu asking for their account names on platforms such as Facebook, Twitter and YouTube. Although the program is billed as voluntary, civil liberties groups fear most travelers will feel pressured to complete the forms, and many fear the program threatens free expression and poses new privacy and security risks.