US military officials say they have disabled advertising trackers on a range of phones and computers, according to letters released by US Senator Ron Wyden and statements given to Reuters, a development that follows reports that commercially available location data had been used to target American forces in the Middle East.

The Air Force tells Wyden it disabled the advertising identifiers on computers and mobile phones two months ago. US Special Operations Command (Socom) says in a separate letter that it “recently” disabled them on its Windows devices. The Army tells Reuters that advertising IDs tied to mobile devices have been disabled since earlier this year.

The disclosures highlight a growing national security concern: that location data collected by the advertising industry and sold by data broker companies that collate and resell personal data can be used to track and target military personnel deployed to war zones.

The Air Force and Socom have declined further comment.