400 million barrels. This is the largest strategic oil reserve release in a single instance by the 32 member countries since the International Energy Agency (IEA) was established 50 years ago. On March 11, when the IEA announced this decision, Brent crude closed at $90.42 that day. Today, 12 days later, oil prices are above $107.

The story begins on February 28. After the United States and Israel launched a joint strike against Iran, Iran threatened to attack tankers passing through the Strait of Hormuz, which is almost paralyzed, the most important oil transportation choke point in the world. According to IEA data, the actual traffic in the strait is currently less than 10% of pre-war levels. Brent crude oil skyrocketed from about $65 before the war to $119.5 intraday on March 9, an increase of nearly 80% in two weeks.

In this context, the IEA has deployed its greatest weapon. The question is, why didn't this weapon work?

The mathematical illusion of 400 million barrels

400 million barrels sounds like a huge number, but when viewed in the context of the gap in the Strait of Hormuz, the proportion is completely different.

In its 50-year history, the IEA has utilized strategic reserves five times, and this is the sixth time. The total amount released in the first four times was about 352.7 million barrels (approximately 50 million barrels during the 1991 Gulf War, 60 million barrels for Hurricane Katrina in 2005, 60 million barrels during the 2011 Libyan Civil War, and 182.7 million barrels in 2022 for the Russia-Ukraine War). This time, the 400 million barrels are even more than the total of the first four times.

But scale does not equal sufficiency.

Before the war, the Strait of Hormuz saw an average of about 20 million barrels of crude oil and refined oil pass through daily, accounting for 25% of global maritime oil trade. According to announcements from the U.S. Department of Energy, 172 million barrels will be released within 120 days. At this rate, the IEA's total daily release of 400 million barrels is about 3.3 million barrels, covering only 17% of the gap. According to estimates by JPMorgan cited by Al Jazeera, the maximum production capacity of IEA member countries is only 1.2 million barrels/day, which is far from sufficient to make up the difference.

To use a more intuitive algorithm: According to the IEA's March report, global daily oil consumption is about 103 million barrels. If all 400 million barrels are dumped into the market at once, it would only last less than four days.

Which historical instances of 'opening the floodgates' really worked?

The results of the IEA's five releases of reserves over 50 years are clearly divided into two categories.

During the Gulf War in 1991, when the IEA announced the release, oil prices plummeted by about 20%, and the decline reached one-third in the following week. After Hurricane Katrina in 2005, the market also quickly stabilized. Both instances share a common characteristic: the source of the supply disruption was being repaired. In the Gulf War, the start of airstrikes meant that Kuwaiti oil fields were expected to recover, and Hurricane Katrina had already passed, with refineries gradually resuming operations.

A counterexample is 2022. After the outbreak of the Russia-Ukraine War, the IEA released 182.7 million barrels, but after the announcement, Brent crude oil did not fall but rose, first soaring to 113 dollars, and then taking several months to slowly decline. The reason is simple: there is no prospect for a quick repair of the supply disruption from Russia.

The situation in 2026 looks more like 2022 than 1991. The Strait of Hormuz remains in a semi-blocked state, with no signs of a ceasefire from Iran. According to analysis by Stanford University researcher Maksim Sonin cited by Al Jazeera, 'this is not a panacea; the market is trading on expectations, and currently, the expectations lean towards concern.' Gregor Semieniuk, an economist at the University of Massachusetts Amherst, more directly pointed out that 'releasing can only buy temporary breathing space; once the release is finished, the firepower is exhausted.'

What determines the oil price response is not how many barrels were released, but whether the source of the supply disruption has been eliminated. The release of reserves is essentially not about 'supplying oil', but about 'buying time', using limited ammunition to exchange for a negotiation window and flexibility in reallocating alternative routes. If time is bought but the source of the disruption is not resolved, oil prices will still rise.

How much ammunition is left?

This raises a longer-term question: after repeatedly 'buying time', is the ammunition depot itself still sufficient?

The U.S. Strategic Petroleum Reserve (SPR) is the largest government emergency oil stockpile in the world. According to data from the U.S. Energy Information Administration (EIA), the SPR peaked at 727 million barrels at the end of 2010. In 2022, the Biden administration released about 180 million barrels to address skyrocketing oil prices due to the Russia-Ukraine War, and the SPR fell to 347 million barrels in June 2023, the lowest level since 1983. After more than two years of replenishment, it is expected to return to about 415 million barrels by March 2026.

Now, 172 million barrels out of the 415 million barrels are to be released. After the planned execution, the SPR will drop to about 242 million barrels, returning to levels seen in the mid-1980s when it was first established. The U.S. Department of Energy has promised to replenish about 200 million barrels within a year of the release, but the last round of replenishment took more than two years to climb from 347 million barrels to 415 million barrels, and the replenishment speed is clearly unable to keep up with the rate of depletion.

Not just the United States. The IEA's 32 member countries held about 1.2 billion barrels of public emergency reserves before the release, and this time, with the release of 400 million barrels, it directly cut one-third.

If the next supply crisis arrives before the SPR is replenished, is the world's 'last ammunition depot' sufficient? This question currently has no answer. The market is unwilling to let oil prices drop precisely because it sees this issue.