The United States Strategic Petroleum Reserve held 289.7 million barrels of crude in the week ending 21 August, according to Energy Information Administration data released on 26 August. That is down 3.7 million barrels on the previous week, and the lowest the reserve has stood since 26 November 1982.

The stockpile is now filled to roughly 41 per cent of its authorised storage capacity of 714 million barrels. It peaked at 726.6 million barrels in January 2010.

What the reserve is, and what it isn’t

The SPR is federally owned emergency crude, stored in solution-mined caverns inside salt domes at four Gulf Coast sites: Bryan Mound and Big Hill in Texas, West Hackberry and Bayou Choctaw in Louisiana. It is not American oil reserves in the ground, and it is not the commercial inventory refiners hold. President Ford established it in 1975 after the Arab oil embargo; filling began in 1977.

The caverns are roughly 2,000 feet down and are emptied by pumping water in at the bottom: oil floats, and is forced out of the top. That mechanism matters later in this story.

How it got here

Before the US and Israeli attack on Iran on 28 February 2026, the reserve held roughly 415 million barrels. After Iran moved to choke off tanker traffic through the Strait of Hormuz — a chokepoint that carried close to a fifth of global oil supply before the conflict — a 172-million-barrel release was authorised in March.

That American drawdown sits inside an International Energy Agency coordinated release, with member states collectively committing around 400 million barrels: the largest emergency stock mobilisation the agency has ever run.

An important mechanical detail gets lost in most coverage. Much of the American drawdown is a lending programme rather than an outright sale. The Department of Energy has contracted out more than 133 million barrels to companies that must return the same volume later, with repayment premiums running as high as 28 per cent on individual deals. On paper, then, a substantial share of what has left the caverns is scheduled to come back — assuming the counterparties can source it and the price environment allows.

“Basically no reserve” is not right — but neither is “still substantial”

When the stockpile dipped below 300 million barrels earlier this month, one widely circulated analyst note said the country effectively no longer has a strategic reserve. That is rhetorical. Nearly 290 million barrels is a large physical stockpile, well above the statutory floor of 252.4 million barrels under the Energy Policy and Conservation Act, and the Department of Energy said in July that the genuine safe-operating floor is closer to 70 million barrels.

But the reassuring reading has a problem too, and it is the one worth understanding. The reserve’s value in a crisis is not the total volume. It is the rate at which oil can be got out — barrels per day, delivered to refineries that can actually process it.

The Government Accountability Office found this year that effective drawdown capacity had already fallen to about 2.7 million barrels per day against a design rate of 4.4 million, with low cavern inventories among the contributing factors. Less oil in a cavern means less pressure and fewer wells drawing usefully, so the inventory figure and the delivery figure decline together. Every barrel removed shrinks the stockpile twice: once in volume, once in flexibility.

The refill problem

Getting back to a comfortable level means buying somewhere in the region of 200 million barrels — analysts have put the bill at up to $18 billion, though that number moves with the crude price and is an estimate rather than an appropriation.

Refilling is also slow by design. Bryan Mound, the largest site, can draw down at up to 1.5 million barrels a day but refills at a capped rate of around 225,000. The asymmetry is physical, not bureaucratic: emptying a cavern is a matter of displacement, filling one is a matter of pumping against pressure through fixed infrastructure. A reserve can be spent in weeks and takes years to rebuild.

There is a genuine disagreement about whether that matters as much as it once did. One view, common among energy economists, is that American production of roughly 13.7 million barrels a day makes the country structurally less exposed than it was in 1975, and that a smaller reserve is a rational trade for having cushioned a real shock. The opposing view is that domestic production does not protect against a price spike in a global market, which is what the SPR was built to blunt, and that a buffer you have already spent is not available for the next disruption. Both are arguments about probability, and neither can be settled until something tests it.

Related: Yemen’s Truce Is Coming Apart, and the Port Is Still Shut.

Sources

Weekly inventory figures from the US Energy Information Administration (series WCSSTUS1) and the Department of Energy, as reported by Anadolu Agency and Energy Factbook; drawdown capacity findings from the Government Accountability Office; loan-programme and refill analysis via 24/7 Wall St. and CNBC.