The amount of Iranian oil that’s readily available to Chinese buyers is rapidly running out, showing the effectiveness of the US blockade of the country’s ports at choking off revenue to Tehran. About 40 million barrels of the Islamic Republic’s crude is sitting on vessels near Singapore, in an area that’s a popular ship-to-ship transfer location for oil heading to China, according to Kpler. However, only 10% of that, or two supertanker cargoes, remains unsold, the data intelligence firm said, citing market participants.

The dwindling stockpiles underscore how sanctions are limiting Tehran’s ability to export crude, forcing Chinese refiners to look for alternative supplies or pay higher prices. Market participants note that the unsold volumes are increasingly scarce, which could tighten spot markets and affect refining margins in the region.

Analysts warn that if the blockade continues, the remaining Iranian cargoes may be snapped up quickly, leaving little room for negotiation. This situation highlights the broader geopolitical tension influencing global oil flows and the strategic importance of key transit hubs like Singapore.

Chinese importers, meanwhile, are monitoring the situation closely, preparing to shift volumes to other Middle Eastern or African sources should the Iranian flow dry up completely.