Documents leaked by former NSA contractor Edward Snowden show that the National Security Agency is gathering a massive amount of data about the location of millions of cell phones all over the world. The news, which contradicts the agency’s claims that it had only experimented with tracking but then abandoned the efforts, is likely to fuel the ongoing scandal over the U.S. government’s surveillance of phone and internet activity.

According to the documents, reported on Wednesday by the Washington Post, the NSA has been harvesting the location of cell phones by using interception equipment plugged into key nodes of phone carriers’ networks. As the Post explains, the system relies on U.S. companies to collect the information at cell towers and other relevant locations to obtain nearly 5 billion records a day about cell phone whereabouts: