The Chokepoint War: Iran Re-Closes the Strait of Hormuz as Dueling Blockades Paralyze Global Oil

On April 18, 2026, Iran announced the second closure of the Strait of Hormuz, reversing a brief reopening that had lasted less than 24 hours [1]. The decision came after President Donald Trump declared the US naval blockade of Iranian ports would remain in force despite a Lebanon ceasefire [3]. Within hours, Iranian Revolutionary Guard Corps gunboats opened fire on two Indian-flagged commercial vessels attempting transit, including the VLCC Sanmar Herald carrying nearly 2 million barrels of Iraqi crude [11]. The incident marked the latest escalation in a crisis that has cut ship traffic through the world's most critical oil chokepoint by over 95% [4] and pushed WTI crude oil above $114 per barrel — a 62.5% increase from a year ago [22].

What began on February 28 as a US-Israeli air campaign against Iran has evolved into something the global economy has never faced: two opposing naval forces simultaneously blockading the same strait, each claiming legal authority, while the 20 million barrels per day that normally flow through the waterway sit stranded [6].

What Flows Through Hormuz — and What's Now Stuck

The Strait of Hormuz is a 21-mile-wide channel between Iran and Oman through which roughly one-fifth of all oil consumed globally transits each day. In the first half of 2025, total oil flows averaged approximately 20.9 million barrels per day, with crude oil accounting for about 14.2 million of those barrels [6]. Saudi Arabia alone sends 6.3 million barrels per day through the strait, followed by Iraq at 3.3 million, the UAE at 2.7 million, and Kuwait at 1.7 million [6].

Source: EIA / IEA

Data as of Mar 1, 2026CSV

The dollar value of this traffic is staggering. At current prices near $100 per barrel, the oil transiting Hormuz on any given day represents roughly $2 billion in crude alone. Qatar also ships the majority of its liquefied natural gas through the strait, making it a dual chokepoint for oil and gas [6]. Beyond hydrocarbons, roughly one-third of global fertilizer trade passes through the waterway, including large volumes of nitrogen-based exports critical to agricultural production [23].

Since the IRGC declared the strait closed on March 2, only 279 ships have transited between February 28 and April 12 — against a pre-war average of approximately 100 per day [4]. The International Energy Agency has characterized the disruption as "the largest supply disruption in the history of the global oil market" [19].

The Price Shock in Real Time

WTI crude was trading below $62 per barrel in late January 2026, before the military buildup began [22]. By the first week of March, after the strait closure, prices had surged past $90. They peaked at $114.58 in early April before briefly dipping when Iran announced it would reopen the strait during the Lebanon ceasefire [22]. That relief was short-lived: the re-closure on April 18 sent markets back into turmoil.

Source: FRED / EIA

Data as of Apr 13, 2026CSV

The Dallas Federal Reserve has modeled three scenarios for sustained closure [5]. A one-quarter disruption would raise the average WTI price to $98 per barrel and lower global real GDP growth by an annualized 2.9 percentage points in Q2 2026. A two-quarter closure pushes the peak to $132 per barrel. A three-quarter closure reaches $167 per barrel. Wall Street analysts and US government officials have begun considering the possibility of $200 per barrel if the standoff extends into 2027 [5].

Source: Dallas Fed

Data as of Mar 20, 2026CSV

The Consumer Price Index already reflects the pressure: CPI hit 330.29 in March 2026, up 3.3% year-over-year, with energy costs as the primary driver [5]. The European Central Bank postponed planned interest rate reductions on March 19, raising its 2026 inflation forecast and cutting GDP growth projections [19]. Oxford Economics has warned that if global oil prices average $140 per barrel for two months, world CPI inflation would peak at 5.8% [19].

Source: FRED / Bureau of Labor Statistics

Data as of Mar 1, 2026CSV

Attacks on Commercial Shipping

The IRGC has launched at least 22 confirmed attacks on merchant ships since February 28, according to ship-tracking data from Kpler [4]. The geographic distribution spans the entire Gulf region: eight ships attacked in UAE territorial waters, six in Omani waters, two each in Iraqi and Qatari waters, and one each in Bahraini, Kuwaiti, Saudi, and Iranian waters [4].

The deadliest wave came on March 11, when at least three vessels sustained damage in a single day. Twenty crew members of the Thailand-flagged bulk carrier Mayuree Naree were rescued by the Royal Omani Navy after the vessel caught fire; three crew members remain missing [9]. Between March 1 and 17, the International Maritime Organization confirmed 17 incidents of damage to commercial vessels, reporting seven seafarers killed, four missing, and ten injured — five severely [10]. Human Rights Watch characterized the deliberate targeting of civilian shipping as "apparent war crimes" [10].

The April 18 incidents marked a new phase. The Indian-flagged Jag Arnav and the VLCC Sanmar Herald were transiting after reportedly receiving prior clearance from Iranian authorities. According to the Sanmar Herald's crew, two IRGC patrol boats approached without radio contact and "shots were fired, resulting in damage to the bridge windows" [11]. India's government summoned the Iranian ambassador, expressing "deep concern" [11].

For comparison, the 2019 Gulf of Oman tanker attacks involved four ships over two incidents in June 2019, with no fatalities. The 2023–2024 Houthi Red Sea campaign struck more vessels over a longer period but was conducted by a non-state actor with less sophisticated weapons. The current IRGC campaign exceeds both in frequency and lethality, employing shore-launched antiship cruise missiles, unmanned aerial vehicles, and explosive unmanned surface vessels [17].

The Dueling Blockades: A Legal No-Man's Land

Both Iran and the United States claim legal authority over the strait — and neither has ratified the UN Convention on the Law of the Sea (UNCLOS), the treaty that most directly governs transit through international straits [12].

Iran's position rests on two arguments. First, Tehran contends that the right of transit passage — which under UNCLOS "shall not be impeded" even in wartime — is a treaty right available only to countries that ratified UNCLOS [12]. Since neither Iran nor the US ratified the convention, Iran argues the older regime of "innocent passage" applies, derived from the 1949 Corfu Channel ICJ ruling and the 1958 Territorial Seas Convention [12]. Under innocent passage, a coastal state has more discretion to regulate and restrict traffic. Second, Iran invokes Article 51 of the UN Charter, claiming its closure is a lawful act of self-defense in response to the US-Israeli armed attack that began on February 28 [21].

The US and most international legal scholars counter that the transit passage regime for international straits reflects customary international law — binding on all states regardless of UNCLOS ratification [12]. Under this view, Iran's closure, toll collection, selective access, and mandatory coordination requirements violate the prohibition on hampering transit passage (UNCLOS Article 44), the non-discrimination requirement, and the rule against suspension [13].

Iran's strongest legal argument, according to the European Journal of International Law, may be the self-defense claim — but this is constrained by the customary international law requirements of necessity and proportionality established in the Nicaragua case [21]. Blocking all commercial shipping, including vessels from neutral states carrying non-military cargo, may exceed what proportionality permits.

The US blockade faces its own legal scrutiny. Under the law of naval warfare, a blockade is a belligerent act lawful only if it meets strict requirements: formal declaration, effectiveness, impartiality, proportionality, and respect for humanitarian and neutral rights [12]. The UN Special Rapporteur on unilateral coercive measures has repeatedly warned that comprehensive sanctions regimes against Iran restrict access to medicine, food supplies, and essential services, raising humanitarian law concerns [21]. The ICJ ruled in Certain Iranian Assets (Iran v. United States) that several US sanctions actions constituted violations of the Treaty of Amity between the two countries [21]. A growing body of international legal scholarship characterizes broad sanctions of this nature as economic warfare, particularly when their effects fall primarily on civilian populations [21].

Neither side has clean hands under international law. Both are operating in a gray zone where armed conflict has weakened the constraints that normally govern passage through international straits.

US Naval Posture: The Largest Gulf Deployment Since 2003

The US has assembled its largest Middle East naval force since the 2003 invasion of Iraq [8]. Three carrier strike groups are deployed to the region: the USS Abraham Lincoln operating in the Arabian Sea, the USS Gerald R. Ford in the Red Sea, and the USS George H.W. Bush, which crossed the Atlantic in March [8].

The impending arrival of additional minesweepers has put at least 27 Navy vessels in the region — roughly 41% of all US ships actively deployed worldwide [8]. Combined, the three strike groups represent more than 200 fixed-wing aircraft, dozens of cruise missile-capable surface combatants, and layered air defense networks incorporating the Aegis Combat System and Standard Missile-6 interceptors [8].

The comparison to Operation Earnest Will (1987–88), the last time the US escorted tankers through Iranian harassment, reveals how much the threat environment has changed. In 1987, the Navy deployed five ships to escort the first reflagged Kuwaiti tankers — a destroyer, two frigates, and two Coast Guard cutters. On the very first convoy, the tanker MV Bridgeton struck an Iranian mine [17]. Iran's current arsenal dwarfs its 1980s capabilities: an estimated 5,000 to 6,000 naval mines, cheap maritime drones deployed on sea and in the sky, and shore-launched antiship cruise missiles that extend threat coverage across the entire strait [17] [18].

USNI Proceedings published an April 2026 analysis identifying a US shortfall in mine countermeasure assets relative to Iran's inventory, calling it "the crisis in mine countermeasures" [18]. Unlike the 1980s Tanker War, Iran is not simultaneously fighting a ground war with Iraq, meaning it can concentrate its full asymmetric naval capability on the strait.

Can Anything Bypass Hormuz?

Two pipelines offer partial bypass routes. Saudi Arabia's East-West Pipeline (also called the Petroline) runs 750 miles from Abqaiq on the Gulf coast to Yanbu on the Red Sea. Its theoretical full capacity is 7 million barrels per day when accompanying natural gas liquids pipelines are converted to carry crude, but wartime operating capacity is estimated at roughly 3 million barrels per day [7]. The UAE's Abu Dhabi Crude Oil Pipeline (ADCOP) spans 248 miles from Habshan to Fujairah on the Gulf of Oman, with a capacity of 1.5 to 1.8 million barrels per day [7].

Together, available bypass capacity is approximately 2.6 million barrels per day — roughly 13% of the 20 million barrels that normally transit Hormuz [7]. And even these alternatives are not guaranteed: in 2019, Houthi drones struck pumping stations on the East-West Pipeline, forcing a temporary shutdown. In March 2026, drone attacks on oil facilities at Fujairah port disrupted loadings at the ADCOP terminus [7].

Iraq's Iraq-Turkey pipeline (the Kirkuk-Ceyhan line) offers another theoretical route, but it has been intermittently offline for years and has limited capacity even when operational. No realistic combination of pipeline alternatives can replace the volume that flows through Hormuz [7].

Who's Running Iran — and What Do They Want?

The killing of Supreme Leader Ali Khamenei in the February 28 strikes reshaped Iran's internal power dynamics. The Assembly of Experts, under IRGC pressure, appointed Mojtaba Khamenei — the late leader's son — as the new supreme leader on March 8, marking the first hereditary succession in the Islamic Republic's history [14]. But Mojtaba has not appeared publicly since his appointment; Iranian media reported he was wounded in the same strike that killed his father [14].

The real decision-making power has shifted to a wartime council of IRGC-linked figures: former IRGC commander Mohsen Rezaei, current IRGC commander Ahmad Vahidi, and Parliament Speaker Mohammad Bagher Ghalibaf [14]. As Alex Vatanka of the Middle East Institute put it: "Mojtaba owes his position to the Revolutionary Guards and as such he is not going to be as supreme as his father was" [14].

The IRGC's strategic calculation, according to analysts at the International Crisis Group and Atalayar, is that a frozen low-intensity conflict maximizes its institutional leverage [15] [16]. Continued disruption of the strait allows the IRGC to maintain internal political dominance, generate revenue from a de facto toll on shipping, pursue nuclear reconstitution, and rebuild proxy networks [15]. A quick resolution — either through capitulation or a comprehensive peace deal — would undermine the IRGC's wartime authority and the extraordinary powers it has accumulated since February.

This creates a structural problem for de-escalation. The faction that controls Iran's military posture in the strait has the least incentive to stand down.

Who Bleeds First: Strategic Reserves and the Clock

The vulnerability of oil-importing nations varies sharply depending on their strategic petroleum reserve levels.

Source: IEA / National Sources

Data as of Mar 12, 2026CSV

Japan holds reserves sufficient for 254 days of consumption, and South Korea for 208 days, giving both countries a buffer measured in months rather than weeks [19]. China's 1.3 billion barrels of emergency reserves cover approximately 120 days of net seaborne crude imports [19]. India's position is more precarious: total petroleum stocks — including commercial and refinery holdings — represent roughly 74 days of supply, though government strategic reserves alone cover far less [19].

The IEA announced a coordinated release of 400 million barrels from member countries' strategic reserves in mid-March, the largest such release in the organization's history [19]. But even this covers only about 20 days of the lost Hormuz flow, buying time rather than solving the underlying disruption.

European nations face compounding pressures. Germany holds approximately 90 days of reserves, but EU member states that rely heavily on Gulf LNG for electricity generation — including Italy and Spain — face an energy mix problem that crude oil releases cannot fully address [19]. UNCTAD has flagged the fertilizer supply disruption as a particular risk for developing countries, where higher energy, fertilizer, and transport costs compound into food price inflation that disproportionately affects the most vulnerable populations [23].

The Macroeconomic Reckoning

The Dallas Fed's modeling provides the clearest framework for assessing knock-on effects at different durations [5]:

Two-week disruption (now elapsed): The initial shock has already materialized. WTI rose from $62 to above $90 in the first two weeks, and the IEA's 400-million-barrel release partially buffered spot prices. However, the disruption has persisted far beyond two weeks.

Six-week disruption (the current trajectory): At one quarter of closure, the Dallas Fed projects WTI averaging $98 per barrel with global GDP growth falling by 2.9 annualized percentage points in Q2 2026. The full-year GDP impact is modeled at -0.2 percentage points [5].

Three-month disruption: If the closure extends through three months, the full-year global GDP impact reaches -0.3 to -1.3 percentage points depending on mitigation efforts. Oil prices would peak between $115 and $132 per barrel [5]. At this duration, the ECB and other central banks face the classic stagflation dilemma: raising rates to fight energy-driven inflation while economic output contracts [19].

The parallels to the 1973 oil embargo are imprecise but instructive. That embargo removed roughly 4.4 million barrels per day from global supply — about 7% of consumption at the time. The current Hormuz disruption removes up to 20 million barrels per day, or roughly 20% of global supply, though bypass pipelines and strategic reserve releases have partially offset the gap [5]. The 1973 shock triggered a global recession and a quadrupling of oil prices. The current crisis, seven weeks in, has already produced a near-doubling from pre-war levels.

Trump's Posture: Blockade and Rhetoric

Trump has framed the crisis in transactional terms. "We can't let a country blackmail or extort the world, because that's what they're doing," he told reporters [20]. On social media, he wrote: "THIS IS WORLD EXTORTION, and Leaders of Countries, especially the United States of America, will never be extorted" [3].

Yet his messaging has oscillated. On April 18 — the same day Iran re-closed the strait — Trump told reporters the US was having "very good conversations" with Tehran [20]. The White House has not specified which war powers authority would govern any escalation beyond the current blockade. The original strikes were conducted under existing authorizations, but a sustained naval confrontation with Iran in the strait would raise questions about whether the 2001 or 2002 Authorizations for Use of Military Force apply — or whether new congressional authorization is required [3].

The fundamental tension in Trump's position is that the US blockade of Iranian ports is itself contributing to the closure. Iran's stated reason for re-closing the strait on April 18 was specifically the continuation of the US blockade [1]. This creates a feedback loop: each side's blockade provides the other's justification.

What Would an Off-Ramp Look Like?

The brief April 17 reopening — lasting less than a day before the re-closure — demonstrated both that de-escalation is possible and how fragile it remains. Iran linked the reopening to the Lebanon ceasefire, suggesting that progress on the broader regional conflict can unlock movement on Hormuz [1]. But Trump's insistence on maintaining the port blockade torpedoed the opening within hours [3].

The International Crisis Group has identified a narrow set of conditions under which Iran's wartime leadership might accept a sustained reopening: a formal end to US-Israeli strikes, lifting of the port blockade, and some form of sanctions relief that the IRGC can present domestically as a concession extracted through strength rather than weakness [16]. The IRGC's need to save face internally — particularly given the wartime council's consolidation of power — means any agreement would need to be framed as an Iranian victory, not a capitulation.

For the US, the challenge is that easing the blockade without a verifiable Iranian commitment to reopen the strait risks appearing to reward the closure strategy. Neither side has a clear path to backing down without the other moving first.

Seven weeks into the crisis, the strait remains functionally closed to most commercial traffic. The economic damage compounds daily. And the institutional incentives on both sides — the IRGC's wartime leverage, the Trump administration's refusal to be seen as yielding to coercion — point toward prolonged confrontation rather than resolution.