Iran Reported to Be Dumping Oil into Gulf Amid Intensifying US Blockade

Satellite images captured between May 6 and 8 by the European Space Agency's Copernicus Sentinel constellation revealed a grey-white plume spreading across roughly 45 square kilometers of sea west of Kharg Island, Iran's main crude export terminal [1][2]. The slick — described by Leon Moreland of the Conflict and Environment Observatory as "visually consistent with oil" — is now at the center of an intensifying dispute over whether Iran is deliberately discharging crude it can no longer export, or whether the release is the unintended byproduct of a storage system pushed past its limits by a US naval blockade now entering its fourth week [1][3].

The Blockade: Scale and Impact

The United States imposed a naval blockade on Iran's ports and coastline on April 13, 2026, following the collapse of the Islamabad Talks aimed at ending the broader US-Israel conflict with Iran that began with airstrikes on February 28 [4]. The blockade is distinct from the Strait of Hormuz crisis — Iran had already closed the strait to commercial traffic on March 4 in retaliation for those strikes — and instead targets Iran's ability to load and ship crude from its own terminals [5].

The Pentagon estimates that Iran lost $4.8 billion in oil revenue between April 13 and May 1, with 31 tankers carrying 53 million barrels of Iranian crude stuck in the Gulf [4][6]. President Trump has claimed the blockade costs Tehran $500 million daily [4]. Treasury Secretary Scott Bessent has said Kharg Island storage is "soon nearing capacity," with daily losses of $170 million [7].

Before the blockade, Iran was exporting approximately 1.84 million barrels per day (bpd) in March 2026. That figure slipped to 1.71 million bpd in April and is estimated to have dropped far more sharply in May as the naval cordon tightened [8][9].

Source: Kpler / Al Jazeera / UANI

Data as of May 8, 2026CSV

For context, Iran exported 2.5 million bpd before the reimposition of US sanctions in 2018. During the Trump administration's first "maximum pressure" campaign in 2019, exports cratered to roughly 400,000 bpd [10]. Iran had rebuilt to an average of 1.68 million bpd in 2025, with China receiving 90% of shipments through a sophisticated "dark fleet" network [10][11].

Storage at the Breaking Point

The storage math at Kharg Island tells much of the story. The terminal has roughly 31 million barrels of capacity and handles 90% of Iran's crude exports [8][12]. As of April 20, utilization had reached approximately 74% — and oil companies typically consider 80% the maximum safe operating level [8][12].

Kpler, the commodity data firm, estimated that Iran could exhaust its remaining crude storage within 12 to 22 days if the blockade persisted [12]. Between April 13 and 21 alone, stocks at Kharg rose by more than 6 million barrels, with the build rate accelerating to 1.7 million bpd in the final days of that window [12].

Iran has taken emergency measures. It reactivated the M/T Nasha, a 30-year-old very large crude carrier that had been anchored and idle, to serve as floating storage [13]. But at net inflows of 1.0 to 1.1 million bpd, an additional 2 million barrels of floating capacity extends the runway by roughly two days [13]. Iran has also begun proactively reducing crude output, using engineering techniques developed during previous sanctions to safely idle and restart wells [7].

Miad Maleki of the Foundation for Defense of Democracies framed the problem directly: "Storage and evacuation capacity are out of sync with upstream output, and the Gulf is paying the price" [3].

Deliberate Dumping or Operational Failure?

The central question — whether the Kharg Island slick represents deliberate Iranian policy — remains unanswered.

Energy analysts have identified two primary non-deliberate explanations. First, Iran may have miscalculated tanker availability and overdelivered crude to export terminals that could not load it [3]. Second, aging vessels pressed into service as floating storage may be leaking [3]. Louis Goddard of Data Desk consultancy noted the slick was potentially the largest since the start of the conflict 70 days ago [1].

The deliberate-dumping hypothesis rests on a different logic. If Iran cannot export oil and faces the prospect of shutting down wells — which risks long-term reservoir damage — disposing of excess crude into the water becomes a grim alternative. Some analysts have suggested this could serve as environmental leverage: creating a pollution crisis that pressures neighboring Gulf states and the broader international community to push back against the US blockade [3][7].

Iran's UN mission in Geneva did not respond to requests for comment. Neither did the US military [1]. Hamid Hosseini, spokesman for Iranian oil exporters, struck a defiant tone in earlier reporting: "We have enough expertise and experience. We're not worried" [7].

The evidence remains circumstantial. Images from May 8 showed no additional active spills beyond the initial slick, and preliminary assessments suggest the plume was beginning to disperse [1][2].

Environmental Exposure Across the Gulf

Maritime risk intelligence firm Windward estimated the slick was moving southeast at roughly 2 kilometers per hour and warned it could reach Qatar's exclusive economic zone within days and potentially drift toward the UAE within two weeks [3][2].

The environmental stakes are shaped by history. During the 1991 Gulf War, Iraqi forces deliberately released approximately 4 million barrels of crude into the Persian Gulf, creating the second-largest oil spill in history [14]. That spill killed an estimated 100,000 wading birds and more than 14,000 other marine animals across 102 species. Oil penetrated Gulf sediments to depths of 50 centimeters in some areas, and research conducted 12 years later found significant quantities still present [14]. Cleanup costs were estimated at $700 million, with much of the work impeded by the ongoing conflict [14].

The current slick is far smaller — 45 square kilometers versus the massive 1991 release — but occurs in a maritime environment already under severe stress. The broader conflict has produced additional oil spills visible from space [15]. CNN reported in April that multiple oil releases across the Gulf were detectable in satellite imagery as a result of the war [15].

Qatar, Kuwait, and Bahrain face the most direct exposure. The 1991 precedent showed that Persian Gulf ecosystems are slow to recover due to the sea's shallow depth, high salinity, and slow water exchange rate [14]. Iranian strikes have also hit desalination plants in the region — the source of 99% of drinking water in Kuwait and Qatar — compounding the vulnerability [16].

The China Factor and Blockade Effectiveness

The blockade's effectiveness hinges on third-party enforcement that key buyers are unwilling to provide. As of mid-April, maritime intelligence showed 157.7 million barrels of Iranian oil on the water, with 97.6% destined for China [9]. In 2025, China purchased an average of 1.38 million bpd of Iranian crude and condensate — roughly 87% of Iran's total observed exports [10][11].

The Washington Post reported on May 7 that ship-to-ship transfers of Iranian oil were continuing far from the blockade zone, including in grey zones near Malaysia and the Gulf of Oman [17]. Iran's sanctions evasion infrastructure — a mature "dark fleet" supply chain — has streamlined tanker voyages from 85-90 days in 2022 to 50-70 days by late 2025 [11].

India has also re-entered the picture. In March 2026, Reliance Industries purchased 5 million barrels of Iranian crude at a $7 premium to Brent, enabled by a US waiver model applied to roughly 170 million barrels of Iranian crude floating offshore [18].

Brett Erickson of Obsidian Risk Advisors offered a pointed assessment: "Washington operates on assumptions Iran will collapse predictably, fundamentally misunderstanding how regimes adapt under sustained economic warfare" [7]. Claire Jungman of Vortexa described the system as "constrained but operational, rather than complete disruption" [7].

Source: FRED / EIA

Data as of May 4, 2026CSV

WTI crude oil prices have surged 87.6% year-over-year to $109.76 per barrel as of May 2026, reaching $114.58 at their April peak — reflecting the combined disruption of the Strait of Hormuz closure and the Iranian port blockade [19].

The Legal Quagmire

The blockade operates in contested legal territory. Neither the United States nor Iran has ratified the United Nations Convention on the Law of the Sea (UNCLOS), the primary international framework governing maritime rights [20][21].

The US argues that transit passage through international straits — including the Strait of Hormuz — has become customary international law binding on all states regardless of treaty ratification [20]. Iran counters with the "persistent objector" doctrine, claiming its consistent opposition to UNCLOS transit passage provisions since the treaty's negotiation exempts it from the rule [20][21].

Legal scholars are divided. A Penningtons Manches Cooper analysis concluded that both blockades are "legally problematic" — Iran's closure of the strait violates transit passage rights, while the US blockade "operates in legally uncertain territory, enforced by a non-signatory state, in a conflict without formal declaration" [20]. An article in The Nation argued that the US interdiction program constitutes an illegal blockade under international law, noting that only six countries — including the US, UK, and France — argue transit passage constitutes customary law [22].

On April 7, Russia and China vetoed a UN Security Council resolution aimed at protecting commercial shipping in the strait. Eleven of 15 council members voted in favor [20]. The veto paralyzed the primary international mechanism for enforcing maritime law in the conflict zone.

The precedents are mixed. The US cited self-defense and UN Security Council resolutions during the 1962 Cuban missile crisis quarantine. The Libya naval blockade operated under explicit UN authorization. The North Korea interdiction program relies on Security Council resolutions specifically authorizing cargo inspections [20]. None of these precedents maps cleanly onto the Iran blockade, which lacks UN authorization and targets a country's commercial exports rather than weapons shipments.

Humanitarian Fallout Inside Iran

The blockade compounds a humanitarian crisis already underway. Iran has experienced daily electricity blackouts since February 2025, each lasting 3-4 hours. In Tehran, northern neighborhoods experienced only 1% of outages while poorer southern districts endured 32% [23]. The 2026 internet blackout has cost many self-employed Iranians — many of them women — access to their online livelihoods [23].

Source: World Bank Open Data

Data as of Dec 31, 2024CSV

Iran's inflation rate was already 32.5% in 2024, and the war and blockade have accelerated the currency crisis [24][25]. US Treasury Secretary Bessent acknowledged in February 2026 that US sanctions policy had "contributed directly" to Iran's currency crisis, which has fueled widespread protests [25].

The Strait of Hormuz closure triggered a "grocery supply emergency" across Gulf Cooperation Council states, which rely on the strait for over 80% of their caloric intake. By mid-March, 70% of the region's food imports were disrupted, driving consumer price spikes of 40-120% [16]. The International Rescue Committee reported that two months into the war, its operational costs had risen 50% due to disrupted logistics and fuel price increases [26].

The pressure is not falling equally on Iran's elites and its general population. Energy rationing, fuel shortages, and consumer inflation hit ordinary Iranians hardest, while the regime retains control of remaining oil revenue streams and the ability to redirect resources. This pattern echoes the 2012-2015 sanctions era, when comprehensive sanctions impoverished Iran's middle class while the Islamic Revolutionary Guard Corps expanded its economic footprint [10].

The Selectivity Question

Iran's strongest counterargument against the blockade centers on selectivity. While the US blockade targets Iran's oil exports on nonproliferation and human-rights grounds, Gulf allies maintain privileged access to alternative export routes. Saudi Arabia reroutes crude through the Red Sea via pipelines that bypass the Strait of Hormuz. The UAE has been running tankers through the blockade zone [27][28].

Iraq, Kuwait, and Qatar — lacking pipeline alternatives — have largely halted or deeply discounted oil sales [27]. The asymmetry has drawn criticism: Gulf producers allied with Washington retain export capacity, while non-allied producers face comprehensive disruption.

The broader conflict has also reshaped OPEC dynamics. Gulf oil producers have shut down approximately 13 million barrels per day of production due to strait disruptions [27]. The UAE announced its exit from OPEC amid the crisis [27]. Brent crude surged past $120 per barrel after the strait closure, and gas prices hit $4 per gallon in the US by March 31 — a 30% spike [16].

Trump signed an executive order in February 2026 authorizing tariffs of up to 25% on countries conducting trade with Iran [25]. But the tariff threat has done little to deter China, which continues to absorb the vast majority of Iranian crude through covert channels [11][17].

What Comes Next

The oil slick near Kharg Island — whether the result of deliberate policy, operational breakdown, or mechanical failure — is a symptom of a system under unsustainable pressure. Iran's onshore storage allows approximately 13 days before wells must shut down or excess crude enters the water [3]. The blockade shows no signs of lifting. And the environmental, economic, and humanitarian consequences are compounding across the Gulf.

The UK, Australia, and the European Union have expressed opposition to the blockade, favoring de-escalation and freedom of navigation [4]. But without UN Security Council action — blocked by Russian and Chinese vetoes — no multilateral enforcement mechanism exists to resolve either the blockade or its consequences.

The 45 square kilometers of oil spreading from Kharg Island may prove to be an isolated incident, as initial assessments suggest the slick is dispersing [1]. Or it may be the first visible sign of an environmental reckoning that the blockade's architects did not account for — and that the region's ecosystems, fisheries, and coastal populations cannot afford.