In a June 29, 2017, photo, U.S. Customs and Border Protection Officer Sanan Jackson, right, helps a passenger navigate the new face recognition kiosks at gate E7 for a United Airlines flight to Tokyo at Bush Intercontinental Airport in Houston. The Trump administration intends to require that American citizens boarding international flights submit to face scans, something Congress has not explicitly approved and privacy advocates consider an ill-advised step toward a surveillance state. (Michael Wyke/Houston Chronicle via AP)

In a June 29, 2017, photo, U.S. Customs and Border Protection Officer Sanan Jackson, right, helps a passenger navigate the new face recognition kiosks at gate E7 for a United Airlines flight to Tokyo at Bush Intercontinental Airport in Houston. The Trump administration intends to require that American citizens boarding international flights submit to face scans, something Congress has not explicitly approved and privacy advocates consider an ill-advised step toward a surveillance state. (Michael Wyke/Houston Chronicle via AP)

HOUSTON (AP) — If the Trump administration gets its way, all U.S. citizens flying abroad will have to submit to face scans at airport security.

Privacy advocates call the plan an ill-advised step toward a surveillance state.

Nonimmigrant foreigners entering the U.S. currently must submit to fingerprint and photo collection.

Congress long ago agreed to extending that to face scans on departure — mostly to keep better track of visa overstays.

Now, the Department of Homeland Security says U.S. citizens must also be scanned for the program to work.

Pilots are under way at six U.S. airports. DHS aims to have high-volume U.S. international airports engaged beginning next year.