According to the National Immigration Forum, the DOJ filed approximately 305 denaturalization cases between 1990 and 2017. Since 2017, the USCIS has been examining approximately 2,500 cases for possible denaturalization. Revoking U.S. citizenship has been historically reserved for those convicted of the most terrible crimes. For example, the U.S. used to reserve this termination of naturalization for war criminals. Since 1979, the federal government denaturalized 107 people because they were war criminals during World War II.