The FBI warned in a letter to Senate Minority Leader Chuck Schumer (D-N.Y.) Monday that it considers mobile applications developed in Russia, including the popular photo-aging app "FaceApp," to be "potential counterintelligence threats."

The backdrop: FaceApp is a Russian-owned mobile application that allows users to upload photos of themselves and see what they may look like at a different age. Experts warned about potential privacy and national security concerns when the app spiked in popularity this past summer, prompting Schumer to request that the FBI and Federal Trade Commission look into the matter in July.

What they're saying: "The FBI considers any mobile application or similar product developed in Russia, such as FaceApp, to be a potential counterintelligence threat, based on the data the product collects, its privacy and terms of use policies, and the legal mechanisms available to the Government of Russia that permit access to data within Russia's borders."

"Russia's intelligence services maintain robust cyber exploitation capabilities ... the [Russian Federal Security Service] can remotely access all communications and servers on Russian networks without making a request to ISPs."

What to watch: The FBI said it will coordinate for notifications and investigations, and will work with applicable task forces if the app is perceived as a threat to "elected officials, candidates, political campaigns or political parties."

Schumer said in a statement: "In light of FBI’s warning that FaceApp, and similar applications developed in Russia, poses a potential counterintelligence threat to the United States, I strongly urge all Americans to consider deleting apps like FaceApp immediately and proceed with extreme caution when downloading apps developed in hostile foreign countries."

The big picture: The letter comes as other foreign apps — namely China's popular video sharing app "TikTok" — are under intense scrutiny from U.S. lawmakers who believe they could pose risks to national security.

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