Sen. Josh Hawley (R-MO) on Wednesday sent a letter to Flock Safety CEO Garrett Langley, raising concerns about the company’s “unprecedented national surveillance network.”

Hawley’s letter comes as Flock faces national pushback over its automatic license plate readers, powered by artificial intelligence, that allow police to better track cars that have been stolen or used in crimes. Flock currently has over 120,000 cameras active across 49 states and has struck deals with thousands of municipalities.