The U.S. Treasury Department announced sanctions against more than 20 individuals, companies, and vessels believed to be involved in Iran's oil and gas exports.

The Treasury Department said on April 15 that all of these entities are part of a network run by Mohammed Hossein Shamkhani, the son of Ali Shamkhani, a senior political advisor to the late Supreme Leader Ali Khamenei, who was also killed in the U.S.-Israel attack.

The sanctions list also includes nine ships, including tankers carrying liquefied petroleum gas (LPG), and several companies based in the United Arab Emirates (UAE).

US Treasury Secretary Scott Bessent at the White House on April 15. Photo: AP

On April 14, the Treasury Department announced it would reimpose all sanctions on Iranian oil. Previously, Washington had granted a one-month permit, valid until April 19, for Tehran to sell its oil stockpiled on tankers offshore.

Treasury Secretary Scott Bessent also signaled a strong stance on the US's readiness to increase pressure. He affirmed Washington's readiness to impose "secondary sanctions" on any country that continues to buy oil from Iran.

"We want to tell countries that if you are buying Iranian oil or if Iranian money is in your banks, we are prepared to impose secondary sanctions," he declared.

The US has imposed a blockade on Iranian ports since April 13. Accordingly, the US will intercept any ships arriving at or departing from Iranian ports in the Persian Gulf and Gulf of Oman, as well as ships that have paid Iran fees to pass through the Strait of Hormuz.

Ports in the Gulf region. Graphic: WSJ

The U.S. Central Command (CENTCOM), the unit in charge of the blockade operation, said on April 15 that it had prevented 10 ships from leaving Iranian ports in the first 48 hours.

Mohsen Rezaei, military advisor to Supreme Leader Mojtaba Khamenei, warned on the same day that Iran would sink U.S. ships in Hormuz if Washington sought control of the strategic strait.