The United States has rolled out another round of sanctions on Iran, this time zeroing in on oil exports by targeting a web of companies tied to one Greek shipper.

According to the US Treasury Department, the measures focus on businesses and vessels linked to Antonios Margaritis, who Washington claims has been moving Iranian oil around the globe. Officials said several more ships and operators have been blacklisted for helping Iran sell oil — revenue the US says supports its weapons programs.

The announcement adds nine companies based in Greece, Hong Kong, the Marshall Islands, and the United Arab Emirates to the sanctions list, along with 12 ships. Many of them sail under “flags of convenience” from other countries.

One example cited was Changbai Glory Shipping Limited, a Marshall Islands-registered company that owns a Liberian-flagged tanker. Since March 2025, the ship has reportedly carried more than four million barrels of Iranian oil to China — still Tehran’s biggest buyer.

The US has been ramping up pressure on Iran’s energy sector since the Washington-brokered ceasefire between Israel and Iran came into effect in June, but it’s far from clear how effective these moves will be given Iran’s steady trade with partners like China.