Iran’s oil loadings plummeted to just 260,000 barrels per day last month—one-sixth of the volume before the United States imposed a de facto naval siege—according to commodity intelligence firm Kpler. Exports from Iranian waters have ground nearly to a halt, leaving the Islamic Republic with few outlets for its crude. Onshore storage facilities, which hold 95 million barrels of capacity, are now almost completely full, with only 13.5 million barrels of headroom remaining. That slim margin equates to roughly a single week’s exports at pre-blockade rates, compelling Tehran to slash production as tanks brim over.

Viewed from Washington, the data vindicate the Biden administration’s quiet but relentless expansion of maritime interdictions, which have turned the Persian Gulf and strategic chokepoints into a tightly enforced cordon. Analysts in London note that the squeeze comes despite Iran’s attempts to maintain a shadow fleet and obscure ship-to-ship transfers. The result is a growing disconnect between potential output and actual sales, with the regime forced to park unsold crude in anchored tankers off its southern coast while it scrambles to preserve market access.

To keep its remaining Chinese customers supplied, Iran has been drawing on floating storage stocks amassed in Asian waters—reportedly around 130 million barrels. These reserves provide a temporary buffer, but they are finite. Maritime tracking suggests that the logistical tether is thinning, raising questions about how long Tehran can sustain even minimal deliveries without freer access to international shipping lanes. The reliance on floating storage also exposes Iran to legal and financial risks if vessels are targeted under secondary sanctions.

Looking ahead, the pressure on Iran’s petroleum sector shows little sign of abating. Global benchmark prices have absorbed the lost barrels with relative equanimity, a signal that the market does not fear a sudden supply gap. This dampens Tehran’s ability to weaponise energy flows in geopolitical negotiations. Should the blockade persist, production cuts could deepen, onshore capacity will be exhausted, and the floating buffer will erode. Asian buyers, already adept at diversifying suppliers, may accelerate their pivot to alternative crudes, leaving Iran’s most valuable revenue stream in a state of semi-permanent atrophy.