The Justice Department has been spying on millions of Americans through the use of fake cell phone towers attached to airplanes.

The Wall Street Journal revealed the existence of the U.S. Marshals Service program, which reached full functionality in 2007.  The Marshals fly Cessna aircraft from at least five metropolitan area airports.  The flights can cover most of the U.S. population.

The devices on the airplanes mimic cell phone towers and allow the Marshals to trick cell phones into reporting registration information.  Tens of thousands of cellphones have their data captured during a single flight.

Justice Department officials would not confirm to the Journal the existence of the program.  An official said that to discuss it would allow criminal suspects or foreign powers to determine ways U.S. officials collect intelligence.  He said nothing is done that does not meet federal law including gaining a court’s approval.

The system reportedly can collect a phone’s information even if you have a phone with encryption capabilities, such as the iPhone 6.