Huawei is the world's third biggest smartphone company—behind Samsung and Apple—and sells phones across the globe. But the Chinese company is virtually unknown in the US. Allegations of stolen intellectual property and spying have dogged Huawei, impeding its efforts to expand its US reach.

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Trump declares TikTok, WeChat “national emergency,” preps bans View more stories Earlier this month, "political pressure" was reported to have derailed an agreement between Huawei and AT&T that would have seen the carrier selling the smartphone company's hardware. Bloomberg is now reporting that Verizon, too, has dropped its plans to sell Huawei phones, including the new Mate 10 Pro. Huawei will still sell phones directly to consumers, and they'll work on US networks. But without the promotion and subsidy that carrier partnerships offer, significant sales volumes are unlikely.

Huawei's difficulties in the US started in 2003, when Cisco accused it of stealing code for router software. More trouble followed in 2008, when Huawei's bid to buy 3Com was blocked. In 2011, the US Department of Defense reported to Congress that it was concerned about the company's close ties to the Chinese military, and a 2012 House Intelligence report echoed these concerns.

In spite of all this, Huawei has subsequently become a major supplier of network and telecoms equipment around the world, especially in Europe and China. The continued pushback means that its networking hardware isn't used by any of the big US carriers; in 2013, Sprint promised to cut its use of Huawei hardware, with the Chinese firm subsequently saying that it was no longer interested in the US market.

Similar spying concerns have been expressed over another Chinese telecoms firm, ZTE.

The US isn't alone in its suspicions; Huawei was blocked from bidding to build Australia's National Broadband Network in 2012, again over espionage fears. By contrast, the UK has deployed Huawei hardware in critical communication systems. To satisfy security concerns, the UK established a facility dedicated to assessing Huawei's software called the Huawei Cyber Security Evaluation Centre, which is overseen from GCHQ.

The traffic isn't all one way, either; in 2014, it was reported that the NSA hacked Huawei systems to find evidence that the company was working with the People's Liberation Army. Huawei was started by a former PLA member, but the company maintains that it is independent of the Chinese government and has no ties to the PLA.

The imminent build-out of the 5G mobile network, offering new opportunities for both network hardware and handset sales, makes Huawei's lack of market access more acute, and, at least among some members of the Trump administration, the move to 5G has further heightened concerns about spying. A proposal for the government to build a national 5G network—widely criticized by parts of the administration as well as the telecoms industry—expressed national security and a reduced reliance on Chinese equipment as its chief rationale.