The Pentagon is ordering retail outlets on US military bases to stop selling Huawei and ZTE phones. The Department of Defense says using the devices could be a security risk.

“Huawei and ZTE devices may pose an unacceptable risk to the department’s personnel, information and mission,” a Pentagon spokesperson said in a statement to The Wall Street Journal. “In light of this information, it was not prudent for the department’s exchanges to continue selling them.”

US military members can still buy Huawei and ZTE devices for personal use from other stores, as there’s no outright ban on that for now. But the spokesperson elaborated that the Pentagon is considering whether it should send out a military-wide advisory about the devices.

Huawei responded to the news in a statement to The Verge: “Huawei’s products are sold in 170 countries worldwide and meet the highest standards of security, privacy and engineering in every country we operate globally including the US. We remain committed to openness and transparency in everything we do and want to be clear that no government has ever asked us compromise the security or integrity of any of our networks or devices.” The Chinese smartphone maker said it was an “employee-owned company” that would continue to expand globally.

US government officials have said that China could order its manufacturers to create backdoors for spying in their devices, although both Huawei and ZTE have denied the possibility. An anonymous source told the WSJ that military leaders are wary that Beijing could use ZTE and Huawei devices to locate soldiers’ exact coordinates and track their movements.

The US government has been making more significant moves against Chinese tech companies since December, although officials have been suspicious of the two companies since before then (such as in 2014 when Huawei was banned from bidding for US government contracts). In a Senate testimony this past February, six major US intelligence heads warned that American citizens shouldn’t use Huawei and ZTE products and services. In January, US lawmakers introduced a bill that would ban US government agencies from using the two companies’ phones and equipment.

For a separate reason, the US Department of Commerce banned US exports to ZTE last month after the company failed to meet a plea agreement when it pleaded guilty to illegally shipping US equipment to North Korea and Iran. ZTE is appealing the ban. Anonymous sources told the WSJ last week that the Justice Department is now probing Huawei for possibly violating sanctions against Iran.

We’ve reached out to the Department of Defense and ZTE for further comment.

Update May 2nd 1:40PM ET: This article has been updated with a statement from Huawei.