Huawei's bad 2018 just keeps getting worse.

The U.S. Department of Justice is investigating whether Huawei violated U.S. sanctions against Iran, according to the Wall Street Journal. Details of the investigation are light, including how far along it is and what exactly the DoJ thinks Huawei may have done.

“Huawei complies with all applicable laws and regulations where it operates, including the applicable export control and sanction laws and regulations of the UN, US and EU,” Huawei said in a statement to The Verge.

Huawei has had a rough first four months of 2018. The company's flagship Mate 10 Pro was reportedly set to launch on AT&T and Verizon, but both carriers are said to have backed out of the deals due to the U.S. government's national security concerns. Then Best Buy stopped selling Huawei products, limiting the company's reach in the U.S. even further.

This news of the Justice Department investigating could hurt Huawei's ability to compete even more. Of course, the company is said to have recently let go of some of its U.S.-based employees as part of a change in focus, so Huawei may already be scaling back its U.S. efforts.