In a Senate Intelligence Committee briefing on Tuesday, the heads of the CIA, FBI, and NSA, the director of national intelligence, and others, expressed concern that the devices could be used as conduits for spying.

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FBI Director Chris Wray said that the intelligence community is “deeply concerned about the risks of allowing any company or entity that is beholden to foreign governments that don’t share our values to gain positions of power inside our telecommunications networks.”

“It provides the capacity to maliciously modify or steal information. And it provides the capacity to conduct undetected espionage,” he continued.

Wray and his intelligence counterparts said they would advise against using Huawei smartphones. U.S. lawmakers seem to be taking such an opinion to heart, with one congressman introducing a bill that would ban the use of Huawei phones for government employees.

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Huawei was founded by a former engineer in China’s People’s Liberation Army, leading Sen. Tom Cotton (R-Ark.) to call the company “effectively an arm of the Chinese government.”

For its part, the manufacturer told CNBC that, “Huawei is trusted by governments and customers in 170 countries worldwide and poses no greater cybersecurity risk than any ICT vendor, sharing as we do common global supply chains and production capabilities.”