The US Treasury on Tuesday sanctioned two individuals and five entities allegedly linked to Iran which it accused of laundering money and importing petroleum products into Houthi-controlled areas of Yemen.

The sanctions target companies based in Yemen and the United Arab Emirates, including Arkan Mars Petroleum and its UAE affiliates, which the US Treasury said coordinated the delivery of $12 million worth of Iranian oil to the Houthis through Yemen’s Ras Isa port.

The transfers allegedly involved Iran’s Persian Gulf Petrochemical Industry Commercial Company (PGPICC), a firm linked to the Revolutionary Guards.

“The Houthis collaborate with opportunistic businessmen to reap enormous profits from the importation of petroleum products and to enable the group’s access to the international financial system,” said Deputy Treasury Secretary Michael Faulkender.

“These networks of shady businesses underpin the Houthis’ terrorist machine.”

The Treasury said the Houthis earn hundreds of millions of dollars annually by taxing petroleum imports and reselling fuel at marked-up prices in areas under their control.