Huawei is preparing its 188,000 global employees for sustained clashes with U.S. authorities. (Ng Han Guan/AP)

The latest move in the protracted battle between the United States and China? It’s not a new slate of tariffs or political jousting but over a FedEx package and an ensuing lawsuit.

After FedEx Corp. refused to ship a Huawei phone from Britain to the United States, and the Chinese Foreign Ministry demanded answers, FedEx filed suit against the U.S. Department of Commerce on Monday to avoid having to follow the most recent restrictions the federal government has imposed on doing business with Huawei.

“FedEx is a transportation company, not a law enforcement agency,” the company said in a statement.

Monday evening, a spokesperson for the Department of Commerce said the body had not yet reviewed the complaint.

Huawei is the world’s biggest seller of telecom network equipment. In May, the Trump administration said the company poses a threat to U.S. national security and placed it on the “entity list,” a move that under Export Administration Regulations (EAR) barred U.S.-based companies from selling Huawei software and chips and providing it with other services.

“FedEx believes that the EAR violate common carriers’ rights to due process under the Fifth Amendment of the U.S. Constitution as they unreasonably hold common carriers strictly liable for shipments that may violate the EAR without requiring evidence that the carriers had knowledge of any violations,” FedEx said in a statement. “This puts an impossible burden on a common carrier such as FedEx to know the origin and technological make-up of contents of all the shipments it handles and whether they comply with the EAR.”

China pushed for an explanation after the package made its way back to a Britain-based writer for PCMag, which covers the computer industry.

In an earlier statement, FedEx said that the package was mistakenly returned because of an “operational error.” The company said that it would accept and transport all Huawei products to addresses other than those of Huawei and its affiliates put on a U.S. national security blacklist. FedEx said it has no “general ban” on Huawei products.

According to Chinese state media, a spokesman for China’s Foreign Ministry said the package error showed that the “U.S. government abuses the concept of national security and uses the state apparatus to suppress a Chinese company on trumped-up charges. This is the root cause of the problem and the cause of the chaos.”

This marks the second time FedEx has been caught among Huawei, the United States and China. Last month, Chinese authorities said they would investigate FedEx for misdirecting packages sent by Huawei.

President Trump is expected to meet with Chinese President Xi Jinping at a Group of 20 summit in Japan this week. But Huawei isn’t banking on those discussions to completely smooth out the trade war. The company is pushing its 188,000 global employees to prepare for sustained clashes with the United States.

At a panel discussion this month at its company headquarters, Huawei founder and chief executive Ren Zhengfei said the U.S. moves to undermine Huawei’s business didn’t stem from national security concerns but an itch to stymie Huawei’s growth.

“We realized when we reached a certain level there would be competition, but it didn’t occur to us the U.S. government would be so determined to take such extreme measures against Huawei,” Ren said.

Jeanne Whalen contributed to this report.