A US appeals court denied Huawei's petition to review the FCC's decision to designate the Chinese telecoms company as a national security threat.
The Federal Communications Commission classified Huawei and ZTE as threats last year, prohibiting the use of federal funds to acquire their equipment.
Last week, the FCC proposed an even more aggressive ban, which would block all purchases of the two Chinese firms, even if the US companies do not use federal funds.
Key to Huawei's efforts to overturn the ruling was its lawyers' insistence that the FCC legally does not have the power to make judgments about national security, as it deals with internal affairs, not foreign relations.
"But no such skullduggery is afoot," the appeals court said in its judgment. "Assessing security risks to telecom networks falls in the FCC’s wheelhouse. And the agency’s judgments about national security receive robust input from other expert agencies and officials."
The judgment notes the numerous agencies that have made claims about Huawei's potential security risks over the years, as well as laws such as the National Defense Authorization Act (FY2018) that banned the DoD from using Huawei equipment.
"In the cases of Huawei and ZTE Corporation, another Chinese telecommunications company, the FCC found the rulemaking record, as well as additional classified information, sufficient to initially designate both companies," the court wrote.
Huawei has repeatedly denied claims that it acts on behalf of the Chinese state.