An unusual amount of highly suspicious cellphone activity in the Washington, D.C., region is fueling concerns that a rogue entity is surveying the communications of numerous individuals, likely including U.S. government officials and foreign diplomats, according to documents viewed by the Washington Free Beacon and conversations with security insiders.

A large spike in suspicious activity on a major U.S. cellular carrier has raised red flags in the Department of Homeland Security and prompted concerns that cellphones in the region are being tracked. Such activity could allow pernicious actors to clone devices and other mobile equipment used by civilians and government insiders, according to information obtained by the Free Beacon.

It remains unclear who is behind the attacks, but the sophistication and amount of time indicates it could be a foreign nation, sources said.

Mass amounts of location data appear to have been siphoned off by a third party who may have control of entire cell phone towers in the area, according to information obtained by the Free Beacon. This information was compiled by a mass-monitoring program supported by DHS and ESD America and known as ESD Overwatch.

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