The measures come as Washington tries to curb the Yemeni group’s attacks on Red Sea shipping lanes amid the war on Gaza.

The US Department of the Treasury announced the measures against the firm Vishnu Inc, registered in the Marshall Islands, on Wednesday, saying that one of its vessels is involved in “illicit shipments”.

It said the cargo was “in support of Iran’s Islamic Revolutionary Guard Corps-Quds Force (IRGC-QF) and Houthi financial facilitator Sa’id al-Jamal, who is sanctioned under US counterterrorism authorities”.

“We remain committed to disrupting the IRGC-QF and the Houthis’ attempts to evade US sanctions and fund additional terrorist attacks,” Treasury official Brian Nelson said in a statement.

“The United States will continue to target the key funding streams that threaten civilians and peaceful international trade.”

The sanctions come as the US pushes to curb Houthi attacks on shipping lanes in the Red Sea. The Yemeni group says it has been targeting Israel-linked ships to help bring an end to the war on Gaza.

The administration of US President Joe Biden labelled the Houthis as “specially designated global terrorists” in January in response to the attacks, enabling strict financial restrictions against the group.

Washington has also led a bombing campaign against Houthi targets in Yemen over the past three months, but the group’s attacks in the Red Sea have persisted.

Monday’s sanctions appear to target both the Houthis and their Iranian allies.

According to the Treasury, Lady Sofia, a Vishnu Inc-owned ship, received a cargo of Iranian commodities from a vessel called Mehle, which is tied to an already sanctioned company linked to al-Jamal.

The Treasury did not specify the nature of the shipment, but Iranian oil and petrochemicals are under heavy US sanctions.

The ship is currently travelling to China, according to the Treasury. The US statement did not say who owns the cargo beyond its Iranian origins and Mehle’s links to al-Jamal.

The sanctions freeze the company’s assets in the US and make it largely illegal for US citizens to do business with the firm.

The US and Iran have seen heightened tensions since 2018, when former US President Donald Trump nixed a multilateral deal that saw Tehran scale back its nuclear programme in exchange for the lifting of sanctions against its economy.

Biden came into office in early 2021 promising to revive the Iran nuclear accord, formally known as the Joint Comprehensive Plan of Action (JCPOA).

But as several rounds of indirect negotiations failed to restore the pact, Washington continued to enforce its sanctions regime against Tehran and piled on more penalties.

JCPOA talks were eventually put on hold, and attempts to revive them were complicated by Iran’s crackdown on anti-government protesters at home in 2022, as well as accusations that Tehran was providing Moscow with drones for use in Ukraine.

Still, the two countries struck a prisoner swap deal last year that led to the release of five US citizens detained in Iran and the unfreezing of $6bn in Iranian assets, to be used for humanitarian purposes.

After Hamas’s October 7 attack in southern Israel, Biden faced bipartisan calls in the US Congress to re-freeze the Iranian funds.

Since then, the war on Gaza — which has killed more than 31,000 Palestinians — has pushed the Iran nuclear file to the back-burner in Washington. Iran has denied seeking a nuclear weapon.