Iranian crude available to Chinese refiners is rapidly running out as the U.S. blockade restricts new exports, forcing buyers to seek Russian crude and other replacement feedstocks.

Chinese refiners are increasing purchases of Iraqi crude as disruptions at the Strait of Hormuz and in the Red Sea complicate traditional Gulf oil supplies to Asia.

A renewed U.S. naval blockade has largely halted Iranian crude exports while extreme diesel-market tightness suggests oil prices may still be underpricing the disruption.