The U.S. sanctioned an individual and businesses it says are involved in an oil-smuggling network that supports Iran’s Islamic Revolutionary Guard Corps-Qods Force.

The Treasury Department on Friday placed financial restrictions on a foreign broker, Mahmood Rashid Amur Al Habsi, who worked with senior Revolutionary Guard officials and facilitated shipments of Iranian oil, including to customers in East Asia, according to a department statement.

The sanctions included businesses associated with al Habsi, including his Oman-based company, Nimr International Llc, which Treasury said facilitates the shipment of Iranian oil. Also sanctioned was Oman-based Orbit Petrochemicals Trading Llc, which facilitated oil deals to obscure the Revolutionary Guard’s involvement, Treasury said.

Senior officials in the Revolutionary Guard use proceeds from Iranian oil exports to help fund the group’s activities, the Treasury Department said.

The move comes as efforts to revive the multinational nuclear deal on Iran have faltered and amid heightened tensions with the inauguration of Iran’s new hard-line president, Ebrahim Raisi.

There also has been a spate of recent incidents including rocket strikes on Israel by Iran-backed Hezbollah militants and the attack on an oil tanker off the coast of Oman. Iran has denied responsibility for the strike on the HV Mercer Street, which killed a Romanian and a British citizen and added to jitters in oil markets.

Iran’s crude output has plummeted since then-President Donald Trump pulled the U.S. out of the nuclear accord in 2018 and tightened sanctions. Some analysts forecast Iran would be able to increase exports from barely anything to around 2 million barrels a day within a few months of deal, which would pressure oil prices. The uncertainty around Iranian supply has complicated OPEC+ policy as the 23-nation group of major exports weighs whether to raise production later this year.

The extra pressure on Iran is supportive of higher oil prices. But as relations with the U.S. show no sign of thawing, it appears increasingly unlikely this extra supply will come imminently.