U.S. intelligence agencies have issued a warning to consumers that Chinese smartphone makers pose a security threat to American customers. They say that the Chinese government can use its smartphones and other products for intelligence gathering. The intelligence chiefs made the comments during a Senate Intelligence Committee hearing earlier this week.

Top officials from the CIA, NSA, FBI and the Defense Intelligence Agency testified in front of the committee about the matter. FBI director Chris Wray said during the hearing, “We’re 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.”

The U.S. intelligence community has long been wary of Huawei. The company was founded by a former engineer in China’s People’s Liberation Army. Congress released a report in 2012 saying the Chinese company should be viewed “with suspicion.” U.S. politicians have said the company is “effectively an arm of the Chinese government.”

Companies and local governments using Huawei products or services creates an issue for the security agencies. The government has previously blocked Huawei from selling technology to some federal agencies. Last week, Republican Senator Tom Cotton of Arkansas introduced a bill that would prohibit the government from contracting with companies that use Huawei products.

Huawei was recently in talks with AT&T regarding a partnership to sell its new Mate 10 Pro flagship smartphones in the U.S., but the discussions ended in January without a deal being reached. The carrier reportedly pulled out of the deal at the last minute due to political pressure.

Huawei is a global leader in networking equipment and its smartphones have proved incredibly successful in recent years. Last year, the company became the world’s second biggest smartphone maker, behind Samsung and ahead of Apple. Its products are currently used in 170 countries around the world.

The company has released a statement regarding what it says it hostility from the U.S. government. A spokesperson for Huawei said in an interview, “Huawei is aware of a range of U.S. government activities seemingly aimed at inhibiting Huawei’s business in the U.S. market.” The company says that it “poses no greater cybersecurity risk than any ICT vendor.”