Huawei sued Verizon over patent infringement claims, the latest in a series of US lawsuits initiated by the vendor, which is seeking unspecified damages from the operator.

The Chinese network equipment maker holds more than 10,000 US patents and claims Verizon is illegally using three related to optical transport network systems. Verizon, in turn claims Huawei is using two of its optical patents without a licence.

Huawei claims the patents are standards essential, which US law requires to be licensed on fair and reasonable terms.

It aims to force Verizon to pay licensing fees along with damages.

Verizon’s patents are not considered standards essential, meaning it would not face restrictions on the fees it charges.

The case is expected to last five days.

Verizon and Huawei are also scheduled for a separate court battle in October regarding two more of the vendor’s patents.

In 2017, Huawei and T-Mobile US settled a patent infringement action initiated by the Chinese vendor in 2016.

Huawei also resorted to the courts in an attempt to overturn a Federal Communications Commission designation of it as a national security threat and last month lost a separate action relating to a block on rural operators employing government funds to purchase its equipment.