The United States on Thursday blacklisted four companies in Iran’s metals sector, as well as one German and three Emirati subsidiaries of Iran’s largest steelmaker that Washington said generate millions of dollars for Tehran’s metals industry, Reuters reports.

The Treasury Department said in a statement that the sales agents together generated tens of millions of dollars annually from the foreign sale of Mobarakeh Steel Company products, contributing to billions of dollars generated overall by Iran’s steel, aluminum, copper and iron sectors.

Thursday’s action targeted Tara Steel Trading GmbH, a Germany-based subsidiary of Mobarakeh Steel Co; United Arab Emirates-based sales agents Pacific Steel FZE, Better Future General Trading Co LLC and Tuka Metal Trading DMCC, all majority-owned by Mobarakeh Steel Co; and Iran-based Metil Steel, also majority-owned by the company.

Mobarakeh Steel Co, previously blacklisted by Washington, accounts for 1% of Iran’s gross domestic product, the Treasury said.