The Treasury Department on Thursday announced sanctions against six companies for their support of a petrochemical firm that does business with Iran.

The six firms, based in China, Iran and the United Arab Emirates, were sanctioned for doing business with Triliance Petrochemical Co. Ltd., a Hong Kong-based broker that has paid millions of dollars for Iranian petrochemicals, crude oil and petroleum products. The company was designated by the Treasury Department in January. 

“The Iranian regime uses revenue from petrochemical sales to continue its financing of terrorism and destabilizing foreign agenda,” said Treasury Secretary Steven Mnuchin. “The Trump administration remains committed to targeting those contributing to Iran’s attempts to evade U.S. sanctions by facilitating the illicit sale of Iranian petroleum products around the world.” 

The State Department is also issuing sanctions against five entities for “knowingly engaging in a significant transaction for the purchase, acquisition, sale, transport, or marketing of petroleum or petroleum products from Iran.” Three executive officers of the sanctioned entities are also being penalized. 

The Treasury Department said Iran uses profits from its petrochemical sales to fund its “destabilizing support to corrupt regimes and terrorist groups” in the Middle East and elsewhere. 

The agency said the sanctions are an effort to target Triliance's use of third-party firms to obtain petrochemicals it bought from Iran, saying the organization uses “numerous other companies to hide its involvement in petrochemical sales.”

The Trump administration has made a tough stance on Iran a focal point of its Middle East policy, most recently announcing it plans to notify the United Nations of its intention to restore "virtually" all sanctions on Iran that were lifted under the Obama-era Iran deal.

Trump withdrew the U.S. from the Iran nuclear agreement in May 2018, angering allies across Europe, though the administration argues that it remains a party to the resolution that enshrined the deal, the U.N. Security Council Resolution 2231, and retains the right to snap back sanctions if it thinks Iran is violating the pact.