The government is rapidly updating the names on its terrorist watch list, with more than 1.5 million added in the last five years.
Those in the Terrorist Screening Database could find themselves on a no-fly list or face additional scrutiny at airports.
The government disclosed the figures in a lawsuit challenging the no-fly list’s constitutionality.
Government lawyers urged a judge to dismiss the case Friday, saying secrets could be exposed.
A federal judge in Virginia did not issue a ruling but expressed deep skepticism of the government’s motion.
The lawsuit was brought by a Virginia man who was stranded in Kuwait after his name appeared on the list. He was 19 when he was detained in 2011. U.S. authorities allowed Mohamed to fly home after he sued.