The Trump administration late Wednesday announced the US portion of a historic worldwide release of government oil in response to the war in Iran, announcing plans to sell 172 million barrels from the US Strategic Petroleum Reserve to steady global markets.

The process, scheduled to begin next week and take approximately 120 days, would constitute a drop of more than 40% of America’s energy backstop and leave the reserve at levels not seen since the early 1980s.

Read more: What's the Strategic Petroleum Reserve, and can it help lower gas prices?

The eye-popping drawdown still represents a smaller amount than what was taken out during President Biden's term at the beginning of Russia’s war in Ukraine. Trump has long criticized that release and vowed to replenish it, even as he's made slow progress in refilling during his first 14 months in office.

Now, his attacks on Iran have flipped the equation, a remarkable turnabout for Trump, who downplayed the chances of releasing oil in response to the crisis just a few days ago.

The latest government data shows about 413 million barrels of oil in the reserve. Removing 172 million of them would take it down to a level last seen in 1982, just five years after the reserve came online.

Announcement of the release was met with some skepticism that the entirety of the promised withdrawal will actually take place if tensions (and oil prices) subside. Questions are also emerging about how much it will help in the short term as tensions stay elevated.

Crude oil prices actually rose following the announcement, with the international benchmark Brent crude (BZ=F) again flirting with $100 per barrel after declines earlier in the week.

For now, at least, the Middle East remains mired in conflict that has been widening in recent days.

The Strait of Hormuz is effectively closed, Iran has escalated its attacks on energy infrastructure across the region, and Iraq has closed its oil port terminals after strikes on two tankers off its coast.

The International Energy Agency (IEA) announced Wednesday that the Group of Seven nations agreed to release a combined 400 million barrels of oil, the largest on record, in response to the tensions.

Read more: How oil price shocks ripple through your wallet, from gas to groceries

In total, the IEA estimates that its members (including the US) hold over 1.2 billion barrels in emergency stockpiles, meaning this planned release would drain global reserves by a third.

The announcement of the releases has also come amid plenty of signals that they could be pared back.

"The releases out of the US strategic petroleum reserve go over about four months," US Secretary of Energy Chris Wright said in a Fox News appearance Wednesday night. "But this conflict, I don't think, goes that long."

Wright has also promised to replace the withdrawals with approximately 200 million barrels "within the next year." In his own social media message on Thursday, the president focused on the upside of high oil prices, saying "we make a lot of money" while maintaining his focus is on stopping the "evil" Iran.

The IEA announcement said the releases would be done "over a timeframe that is appropriate to the national circumstances of each Member country" and that "it will also continue to closely monitor global oil and gas markets and to provide recommendations to Member governments, as needed."

These signals have led some experts to suggest the final move could be lower than initially promised.

Analysts at Goldman Sachs, in a note Wednesday, projected that the promise of 400 million barrels may translate to 254 million barrels in the end if the war winds down and the Strait of Hormuz is reopened.

The analysts suggested that the full release would only occur "under longer/much longer disruptions."

Biden’s withdrawals, meanwhile, actually lived up to initial promises. In March 2022, he announced plans to release 1 million barrels per day for 180 days, calling it a "moment of peril" for the world.

That was followed by another release of 15 million barrels in October of that year.

Since the US reserve came online in 1977, most presidents have tapped it, especially after its initial buildup under Jimmy Carter and Ronald Reagan.

In fact, 4 of the last 5 presidents have left office with less in the reserve than when they entered. Those withdrawals were due both to direct presidential actions and congressionally mandated withdrawals, with lawmakers often looking to oil sales as a way to pay for other priorities.

George W. Bush added to the reserve during his tenure, but Bill Clinton, Barack Obama, Trump (in his first term), and Biden all oversaw a lower SPR level when they left Washington than when their terms began.

Biden's withdrawals were the most dramatic. The year after the war broke out in Ukraine, the SPR reached its lowest level in recent history, down by over 290 million barrels of oil between January 2021 and June 2023. Then, a slow restocking started.

In the end, Biden left office with about 243 million fewer barrels of oil in the reserve than when he entered.

Ben Werschkul is a Washington correspondent for Yahoo Finance.

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