The U.S. Department of Homeland Security operates a secret algorithm called ATLAS that screens naturalized citizens for potential fraud or national security concerns, flagging them for denaturalization. The system, hosted on Amazon Web Services, analyzes biometric and other data from various federal databases, and its rules are undisclosed. Human reviewers then decide whether to refer flagged individuals to Immigration and Customs Enforcement for possible deportation. Critics allege the algorithm relies on inaccurate data and lacks transparency, leading to wrongful denaturalization proceedings.