Earlier this week, U.S. Customs and Border Protection (CBP) confirmed to media outlets that surveillance images of travelers taken at an undisclosed land port had been compromised as part of a cyber attack on one of the agency’s subcontractors.

According to The Washington Post, those images included the faces and license plates of people crossing the border and are used as part of an ongoing facial-recognition program that tracks people going into or out of the U.S.