U.S. Blockade Strands Dozens of Iranian Tankers and Sinks Exports

The naval blockade imposed by the United States on Iran is keeping dozens of loaded tankers immobilized along the Iranian coast and in Indo-Pacific waters, according to United Against Nuclear Iran (UANI). The group reported that at least 50 vessels remain stranded near the country, while others are waiting off Sri Lanka and Oman, unable to return to Iranian ports. According to Kpler data cited by Reuters, Iran did not load any crude at its terminals during September, the first month without shipments since the firm began monitoring the country in 2013, coinciding with Bloomberg estimates showing the same drop to zero since the start of the war in February.

Within the Persian Gulf, at least 11 loaded tankers remain at anchor east of Kharg Island, Iran's main export terminal, with another five further south, and no vessel was seen loading there on Monday. Outside the Gulf, 20 Iranian-flagged vessels are loitering off Sri Lanka after leaving the Galle anchorage, while the tanker Diona remains in deep water off Duqm, Oman. Treasury Secretary Scott Bessent told Axios that this week the country would have no oil at sea "for the first time in history," and a U.S. military count put the number of redirected vessels at 130, a figure that Central Command (Centcom) later updated to 135 diverted vessels and four disabled during the three months of the reimposed blockade.

UANI documented that Iranian exports, measured by crossings of the blockade line, fell from 966,133 barrels per day in July to 49,677 bpd in August and 50,789 bpd in September, with China receiving no newly exported barrels under that methodology. The group estimates that around 9 million barrels of Iranian crude were transferred during September through ship-to-ship operations in Malaysian waters, bound for independent Chinese refineries, which reduced the floating storage accumulated before the blockade to just about 10 million barrels at the Outer Port Limits of Malaysia's Eastern anchorage.

Despite the blockade, Reuters reported that Iran has managed to export some liquefied petroleum gas and jet fuel since July, concealing these cargoes among ship-to-ship transfers involving other Gulf producers off Oman. UANI tracked at least eight gas carriers with Iranian LPG that left the Gulf of Oman since mid-July, for an estimated total of 4.1 million barrels, in addition to a jet fuel cargo that arrived in Myanmar in September. Centcom, which described its blockade as "ironclad," reimposed it on July 14 after the collapse of a previous understanding with Tehran, and Washington added sanctions last week on 17 vessels linked to the transport of Iranian crude and petrochemicals.

Pressure on maritime traffic in the region has also driven up the cost of ship fuel: in Singapore, the world's leading bunkering hub, VLSFO rose from $509 per ton on February 27, the eve of the war's start, to $886 this week, while HSFO climbed from $432 to $764, increases of 74% and 77% respectively. For a shipowner purchasing 1,000 tons of fuel, that represents an additional cost of about $377,000 compared to pre-conflict prices.