Aircrafts by the U.S Department of Justice are being used to imitate phone reception towers to collect people’s data.

This is intended to target people being investigated by the government and law enforcement, according to the Wall Street Journal. It was reported on Thursday that while data from people not under investigation is also collected, the technology that enables the imitation cell phone reception can also disconnect from the phones of those people. Sources for the information provided to the WSJ weren’t named.

The machines used to create the reception and collect the data are known as “dirtboxes,” according to PCMag, which are on Cessna airplanes controlled by the U.S Marshals Service. The aircraft’s device will show up on a cell phone as the best signal, in which users would connect to that signal and the dirtbox would receive their information.

No information on the length of time or precise number of flight operations were given to the WSJ, and an unnamed official at the Justice Department didn’t confirm or deny if the operation actually existed.