This summer, the biggest pop culture sensation isn't a movie or even the summer Olympics, but rather the new augmented-reality app Pokemon Go, which has become the most popular mobile game app of all time, with more than 100 million downloads. Despite its popularity, the game has seen its fair share of controversy, with a number of security concerns and some players even falling off cliffs while playing this game. Today we have word that the Pentagon has issued a ban on the game due to foreign espionage concerns.

The Washington Times' source reveals that the Pentagon has banned this game from all Department of Defense facilities, over concerns that the game could "facilitate foreign spying." A memorandum was sent on July 19, warning all Pentagon officials and contractors that playing this game "poses a risk" to secure facilities. Pentagon officials are worried that data obtained by the game could provide accurate locations of the rooms where secrets are stored.

The Pentagon is also worried that the game may provide spies with access to data on Pentagon officials who know about these secure locations that may be used during cyber attacks. Last month, shortly before the memo was issued, a Pokemon "gym," which is a central hub for Pokemon activity within the game, appeared at the Pentagon within the app, but it later disappeared. The official Twitter page for the U.S. Marines posted a photo of the popular character Pikachu who surfaced on a firing range within the app.

Related: 2 New Pokemon Games Are Coming to Nintendo Switch

It's also worth noting that, last month during Comic-Con, filmmaker Oliver Stone warned that Pokemon Go is a "new level of invasion" and a form of "surveillance capitalism." Earlier that month, a report from the New York Times revealed that users who downloaded the app through their iPhones were allowing the app to download massive amounts of users' private data, if they signed in to the app through their Google account. A software update was later released which limited the amount of data the game's developer, Niantic, Inc., can collect from each user.

This report comes just weeks after the Israeli government banned the app from its bases, and from being downloaded on government-issued electronic devices. Regardless of the security concerns, the app is still wildly popular, and has lead to Legendary finalizing a deal for a new live action Pokemon movie centering on Detective Pikachu, but we don't know much about the story quite yet. Take a look at the U.S. Marines' tweet from last month, and stay tuned for more on Pokemon Go.