FedEx apologized for another Huawei delivery “mistake,” after it returned a package that contained a Huawei phone without delivering it to its receipient.

The firm said it returned a package due to an “operational error,” and that it would deliver all products made by Huawei Technologies to addresses other than those of Huawei and affiliates placed on a U.S. national security blacklist.

PC Magazine reported that its writer in Britain had attempted to send a Huawei P30 handset to a colleague in the United States. Fedex returned the phone and told the sender that it could not deliver the package because of a “U.S. government issue” with Huawei and the Chinese government.

The incident comes as Chinese authorities investigate FedEx for misrouting packages sent by Huawei last month. Meanwhile, China is also drawing up an Unreliable Entities List of foreign firms, groups and individuals.

The list is China's response to the U.S. Entity List that Huawei was added to in May, essentially barring it from buying U.S. technology upon which it was heavily reliant.

United Parcel Service has also confirmed it would not ship to Huawei addresses on the Entity List but had no “general ban” on Huawei products.

On Sunday, Huawei tweeted it was not within FedEx’s right to prevent the delivery and said the courier had a “vendetta.”

The United States and China have been engaged in a trade fight for nearly a year on issues such as tariffs, subsidies, technology, regulations and cyber security.