Huawei today filed a lawsuit against Verizon that accuses the U.S. carrier of illegally using 12 Huawei patents in its networks.

“Verizon’s products and services have benefited from patented technology that Huawei developed over many years of research and development,” said Song Liuping, Huawei’s chief legal officer, in a statement. “Huawei is simply asking that Verizon respect Huawei’s investment in research and development by either paying for the use of our patents, or refraining from using them in its products and services.”

The China-based vendor filed the patent infringement lawsuits in the Eastern and Western U.S. District Courts in Texas. Huawei has its U.S. headquarters in Plano, Texas.

Before filing the lawsuits, Huawei says it negotiated with Verizon “for a significant period of time,” but the companies could not reach an agreement. Huawei first started pressing Verizon to pay licensing fees a year ago, according to The Wall Street Journal.

Verizon issued a statement this morning calling Huawei’s lawsuit a PR stunt and suggesting that it has more to do with the larger U.S.-Huawei tensions than with Verizon itself.

“Huawei’s lawsuit filed overnight, in the very early morning, is nothing more than a PR stunt,” it said. “This lawsuit is a sneak attack on our company and the entire tech ecosystem. Huawei’s real target is not Verizon; it is any country or company that defies it. The action lacks merit, and we look forward to vigorously defending ourselves.”

Last year multiple federal agencies and the White House imposed trade sanctions and formally banned Huawei from supplying 5G equipment to domestic operators, purchasing American-made products, or receiving federal subsidies. The U.S. government maintains that Huawei poses a threat to America’s national security.

Huawei has repeatedly denied all allegations of espionage and intellectual property theft. In March 2019 the vendor filed a lawsuit against the U.S. government, challenging an order that bans the government, its contractors, and suppliers from purchasing Huawei equipment or services. And in December Huawei filed a legal challenge against the U.S. Federal Communications Commission after that agency deemed Huawei a security threat and barred rural U.S. operators from using its equipment in their networks.

In its statement about the Verizon lawsuit, Huawei says it has signed more than 100 license agreements with major carriers and telecom equipment vendors the United States, Europe, Japan, and South Korea over the past 20 years. Since 2015, Huawei says it has received more than $1.4 billion dollars in patent license fees and paid more than $6 billion dollars to use patented technologies developed by its industry peers. It says 80% of those license fees have gone to U.S. companies.