US Treasury Secretary Scott Bessent said Iran loaded “zero” crude oil onto tankers in September, claiming the Trump administration’s sanctions have cut off Tehran’s most critical revenue stream.

“The Trump Administration is cutting off the Iranian regime’s most critical source of revenue,” Bessent wrote on X on October 1. He described Operation Economic Outcast, launched August 24, as severing the economic lifelines funding what he called Tehran’s “terrorist agenda.”

Preliminary tanker-tracking data from Bloomberg, Kpler and Vortexa showed no Iranian crude loadings in September. Iran had loaded an estimated 220,000 to 255,000 barrels per day of crude and condensate in August, according to Kpler and Vortexa data cited by Reuters.

Iran continued supplying some Chinese buyers from oil held in floating storage near Singapore, but those stocks are expected to decline without new cargoes leaving Iranian ports.

The Treasury Department launched Operation Economic Outcast on August 24 as a government-wide campaign targeting Iran’s financial networks, oil smuggling and sanctions evasion. In a separate post, Bessent said the administration was also targeting Iranian rail and automotive conglomerates, which he said had been co-opted by the regime and the Islamic Revolutionary Guard Corps.