The U.S. intelligence agencies aren't thrilled about the idea of U.S. citizens using phones from certain Chinese manufacturers.

According to a CNBC report, the heads of six intelligence agencies -- including the CIA, FBI and NSA -- told the Senate Intelligence Committee on Tuesday that they wouldn't recommend U.S. citizens to use products or services from China's Huawei or ZTE.

"We're deeply concerned about the risks of allowing any company or entity that is beholden to foreign governments (...) to gain positions of power inside our telecommunications networks," said FBI Director Christopher Wray. "It provides the capacity to maliciously modify or steal information. And it provides the capacity to conduct undetected espionage."

ZTE, another smartphone/telecommunications giant with strong ties to China's government, has also been named as problematic during the hearing.

This is in line with a recent Bloombergreport, which said that Verizon has dropped plans to sell Huawei phones in the U.S. due to pressure from the government. Huawei has been labeled as a spy threat as far back as 2012, when it was primarily a network equipment manufacturer. The company invariably denied the spying allegations.

"Huawei is aware of a range of U.S. government activities seemingly aimed at inhibiting Huawei's business in the U.S. market. Huawei is trusted by governments and customers in 170 countries worldwide and poses no greater cybersecurity risk than any ICT vendor," a Huawei spokesman told Mashable. It's worth noting that nearly all popular smartphones, including Apple's iPhone, are almost entirely made in China, though admittedly Apple has the ability to thoroughly control what goes inside its phones.

Last week, Arkansas Senator Tom Cotton and Florida Senator Marco Rubio introduced a bill that would block the U.S. government from buying or leasing network equipment from Huawei or ZTE.

Huawei, which is now the second largest smartphone manufacturer in the world, had big plans for expansion into the U.S. market this year, but with no deal with a U.S. carrier in place (AT&T pulled out of a deal about a month before Verizon did), following through with those plans will be a tall order.