The Largest Oil Disruption in History: How the Iran War Shut Down the Strait of Hormuz and Triggered a Global Energy Crisis

Twelve days after joint U.S.-Israeli strikes on Iran began, the International Energy Agency has declared what energy analysts had already concluded: the world is experiencing the largest oil market disruption ever recorded. With roughly 20% of global oil supply choked off at the Strait of Hormuz and spare production capacity effectively eliminated, the crisis dwarfs every previous supply shock — including the 1973 Arab oil embargo, the 1990 Gulf War, and the 2022 Russian invasion of Ukraine [1][2].

The IEA's 32 member countries have responded with a historic coordinated release of 400 million barrels from strategic petroleum reserves, the largest such drawdown in the agency's 51-year existence [3]. But analysts warn this measure — while unprecedented — can only partially offset a disruption removing nearly 15 million barrels per day from global markets [4].

The War That Broke the Oil Market

On February 28, 2026, U.S. and Israeli forces launched nearly 900 strikes in a 12-hour opening salvo targeting Iranian missiles, air defenses, military infrastructure, and leadership compounds. The strikes killed Iran's Supreme Leader Ali Khamenei and destroyed critical military installations across the country [5][6]. By March 10, U.S. Central Command reported that American forces alone had struck more than 5,000 targets in Iran [5].

Iran's retaliation was swift and consequential for global energy markets. The Islamic Revolutionary Guard Corps fired over 500 ballistic and naval missiles and nearly 2,000 drones, with roughly 60% aimed at U.S. targets in the region and 40% directed at Israel [5]. Critically, the IRGC declared that "not a litre of oil" would pass through the Strait of Hormuz, issuing warnings to all commercial shipping that the waterway was closed to navigation [7].

The Strait of Hormuz, a narrow passage between Iran and Oman at the mouth of the Persian Gulf, ordinarily facilitates the transit of approximately 20 million barrels of oil per day — roughly one-fifth of all global seaborne oil trade [8]. Within days, tanker traffic through the strait ground to a near-complete halt as shipping companies and insurers refused to risk their vessels under Iranian threats of attack [1].

A Disruption Without Precedent

The scale of the supply shock is staggering. According to Rapidan Energy Group, whose proprietary dataset covers every major oil supply disruption since 1950, the current crisis has exceeded any prior event by more than double [4]. The 1956 Suez Crisis disrupted roughly 2 million barrels per day, about 11.4% of global demand. The 1973 Arab oil embargo removed 4.3 million bpd, or 7.4% of supply. The 1990 Gulf War saw losses of roughly 4.3 million bpd, around 6.5% of global demand [9][4].

The Iran war has disrupted approximately 20% of global supply for nine consecutive days and counting — more than double the previous record [4].

Source: Rapidan Energy Group / CNBC

Data as of Mar 12, 2026CSV

What makes this crisis uniquely dangerous, analysts say, is not just the volume of oil taken offline, but the simultaneous elimination of the world's spare production capacity. Saudi Arabia and the United Arab Emirates — which together held the overwhelming majority of global spare capacity, estimated at roughly 3.5 million barrels per day — are themselves trapped behind the Hormuz blockade [4][10]. Even as OPEC+ agreed to a modest 206,000 bpd production increase for April, analysts noted the decision was largely symbolic: the oil cannot reach global markets if it cannot transit the strait [10].

"The conflict has not only taken offline a historically high share of global supply — it has simultaneously disrupted the primary holders of spare capacity," Rapidan Energy Group stated in its analysis. "Effective spare capacity has been zeroed out" [4].

The Cascading Shutdown

The Hormuz closure set off a cascading series of production shutdowns across the Persian Gulf. Iraq began shutting down operations at the massive Rumaila oil field on March 3 as storage capacity filled up, with crude output from Iraq's southern fields plunging roughly 70% — from approximately 4.3 million bpd to about 1.3 million bpd [11][12].

Kuwait declared force majeure on March 7 and began cutting production, explicitly citing "Iranian threats against safe passage of ships through the Strait of Hormuz" [12][13]. The UAE followed suit, also beginning output cuts as storage facilities approached capacity [13].

Saudi Arabia, the world's largest oil exporter, started reducing production by March 9 as the near-complete blockade of the strait caused its storage facilities to overflow [14]. While the kingdom has some limited ability to export through the Red Sea via the East-West Pipeline, this alternative route can handle only a fraction of normal export volumes [14].

Oil Prices: A Shock in Real Time

Crude oil markets have experienced extreme volatility since the strikes began. Brent crude, the global benchmark, jumped from roughly $71 per barrel on February 27 to over $77 on March 2 as markets digested the initial shock [15]. By March 5, with the Hormuz closure tightening, Brent surpassed $88 per barrel. On March 8, it broke through $100 for the first time since 2022, and on March 9 it scraped $120 — its highest level in four years [7][15].

WTI crude, the U.S. benchmark, has followed a similar trajectory, rising from roughly $67 on February 27 to $94.65 by March 9 — an increase of more than 41% in less than two weeks [15].

Source: FRED / U.S. Energy Information Administration

Data as of Mar 12, 2026CSV

The price surge has immediately hit consumers. The U.S. national average gasoline price jumped from $2.94 per gallon in late February to $3.50 per gallon by the week of March 9 — a 19% increase in barely two weeks [16]. Analysts at the Center for American Progress warned that rising fuel costs would ripple through the broader economy, increasing transportation, shipping, and production costs across virtually every sector [17].

Source: FRED / U.S. Energy Information Administration

Data as of Mar 12, 2026CSV

The IEA's Historic Response

On March 11, the IEA announced that its 32 member countries had unanimously approved the release of 400 million barrels of oil from strategic reserves — the largest coordinated stockpile drawdown in the agency's history [3][18]. The previous record was a 60 million barrel release in 2011 during the Libyan civil war [3].

The United States is contributing the lion's share: 172 million barrels from the Strategic Petroleum Reserve, beginning next week. The SPR currently holds approximately 415 million barrels — about 58% of its authorized capacity of 714 million barrels — already near its lowest level in three decades following large drawdowns in 2022 [19][20]. The Trump administration said it had arranged to replace the released reserves with approximately 200 million barrels within the following year [19].

Other major contributions include South Korea (22.46 million barrels), the United Kingdom (13.5 million barrels), and releases from Germany, Japan, and Austria [3]. The U.S. release alone will take approximately 120 days to fully deliver [19].

However, energy experts were quick to temper expectations. "The SPR can help, but it's not a silver bullet," one analyst told PBS News [20]. The IEA drawdown can offset only a fraction of the roughly 15 million bpd net supply loss of crude and refined products flowing through Hormuz [1]. At the pace of the total coordinated 400 million barrel release, it would cover the Hormuz shortfall for less than a month.

Global Economic Fallout

The economic consequences are already rippling across the globe. Every 10% increase in oil prices, if sustained for most of the year, pushes up global inflation by 0.4% and reduces worldwide economic output by as much as 0.2%, according to IMF Managing Director Kristalina Georgieva [21].

Global stock markets have declined sharply. The Dow Jones fell over 400 points and the S&P 500 dropped 0.7% on March 2 alone, while European and Asian indexes fell 1-2% [21]. Saudi Aramco's CEO issued a stark warning that the Iran war could bring a "catastrophic" shock to the global oil market and the broader economy [22].

For Europe, the situation is particularly acute. Already grappling with elevated energy costs since 2022, sustained higher oil prices threaten to push the continent to the brink of recession [21]. The Chatham House think tank warned that the conflict's impact on energy markets could prove more durable than the immediate military operations [23].

The Road Ahead

The IEA and energy analysts agree on one uncomfortable conclusion: strategic reserve releases are a stopgap, not a solution. Oil prices are likely to continue rising until either a ceasefire is reached, the military threat to Hormuz shipping is neutralized, or significant alternative supply routes are established [1].

The Trump administration has signaled it is considering military options to reopen the strait, with President Trump stating the U.S. was "considering taking over the Strait of Hormuz" [24]. But any such operation would carry enormous risks, both military and economic, in an already volatile theater.

OPEC+ has limited room to maneuver. Its spare capacity — the global oil market's traditional safety valve — sits behind the same blockade that is causing the crisis. Even if Saudi Arabia and the UAE could produce at maximum capacity, the oil has nowhere to go as long as the strait remains effectively closed [4][10].

Meanwhile, Iran's IRGC has shown no signs of relenting. The organization has continued to threaten any vessel attempting to transit the strait, and shipping insurers have categorized Hormuz-bound transits as uninsurable under current conditions [7][8].

Historical Context and the IEA's Origins

There is a bitter irony in the current crisis. The IEA itself was created in 1974 as a direct response to the 1973 Arab oil embargo — designed specifically to coordinate the strategic reserves that member nations built to prevent a future oil weapon from being wielded against them [9]. Five decades later, those reserves are being deployed in the largest coordinated release ever, against a disruption that exceeds even the crisis that birthed the agency.

The difference is one of scale and structural vulnerability. In 1956 and 1973, spare capacity existed elsewhere in the global system. In 2026, the world's spare capacity sits in the Persian Gulf, behind the very chokepoint that has been shut down [4]. The buffer is gone.

As Brent crude prices closed at $91.98 on March 11 — down from their $120 peak but still roughly 30% above pre-war levels — markets appeared to be pricing in a protracted disruption with no clear resolution in sight [15]. The IEA's record reserve release bought time, but the fundamental question remains unanswered: what happens when the reserves run out and the strait is still closed?