US Threatens Sanctions on Shipping Firms That Pay Iran Strait Tolls

The OFAC Warning

On May 1, 2026, the US Treasury Department's Office of Foreign Assets Control (OFAC) issued an alert that put the global shipping industry on notice: any company that pays Iran for passage through the Strait of Hormuz risks being cut off from the American financial system [1]. The warning covered payments in any form — cash, digital assets, cryptocurrency, informal swaps, and even nominally charitable donations to organizations like the Iranian Red Crescent Society [2].

The alert did not set a specific compliance deadline. Instead, it invoked the broad architecture of existing Iran sanctions — the International Emergency Economic Powers Act (IEEPA), Executive Order 13846, and the Comprehensive Iran Sanctions, Accountability, and Divestment Act of 2010 (CISADA) — to remind shipping firms, insurers, and financial institutions worldwide that facilitating toll payments could trigger designation on OFAC's Specially Designated Nationals (SDN) list [3]. That designation would freeze any US-held assets and bar American companies from doing business with the sanctioned entity.

For non-US firms, the threat is secondary sanctions: foreign financial institutions that process toll payments could lose access to the US dollar clearing system, effectively cutting them off from global commerce [4].

The Chokepoint That Feeds the World

The Strait of Hormuz, a 21-mile-wide passage between Iran and Oman at the mouth of the Persian Gulf, is the single most important oil transit point on Earth. In the first half of 2025, approximately 20.9 million barrels per day of crude oil and petroleum products passed through it — roughly 20% of global oil trade [5]. Nearly 15 million barrels per day of crude alone, about 34% of global seaborne crude trade, flowed through the strait [5].

Source: EIA / IEA

Data as of Apr 30, 2026CSV

The waterway is equally critical for liquefied natural gas (LNG), with Qatar — the world's largest LNG exporter — entirely dependent on Hormuz for its shipments. Before the crisis, roughly 25% of global LNG trade transited the strait [6].

That flow collapsed after February 28, 2026, when the United States and Israel launched an air campaign against Iran. In retaliation, Iran attacked US military bases and Gulf state allies, then effectively closed the strait to normal commercial traffic [7]. By March 2026, transit volumes had plummeted to an estimated 2.1 million barrels per day — a 90% reduction from pre-crisis levels [5].

How Iran's Toll System Works

Iran's toll regime emerged from the wreckage of the strait's closure. Beginning in late March, Tehran offered select vessels a way through: ships from countries Iran considers "friendly" could apply for government-to-government clearance, receive a radio code, and be escorted by Islamic Revolutionary Guard Corps (IRGC) patrol boats along a northern route closer to Iranian territorial waters, skirting around Larak Island [8].

The price: up to $2 million per vessel, payable in Chinese yuan or Bitcoin [9]. On a 2-million-barrel tanker, that works out to approximately $1 per barrel [10]. Iran has also floated a revenue-sharing arrangement with Oman, though Oman has publicly rejected participation, citing its commitments to international maritime transport agreements [11].

About 100 vessels transited the strait in the month following the toll's introduction, though most were Iranian-owned or flagged. Indian, Pakistani, and Chinese vessels accounted for the bulk of third-party transits [8]. Maritime analyst C. Uday Bhaskar estimated that during the brief ceasefire window in mid-April, only three to five non-Iranian ships passed through [11].

Iran's deputy speaker of parliament announced in late April that the "first revenue" from the tolls had been deposited into the Central Bank of Iran's account [12]. Iranian officials have projected the system could generate $20 million per day from oil tankers alone, with $600–800 million per month possible if LNG carriers are included [13]. Independent analysts at Iran International have called the $100 billion annual revenue projection floated by some Iranian media a "myth," noting that actual collections have been severely limited by the ongoing dual blockade [13].

The Legal Battle: UNCLOS vs. Iran's Pre-Convention Claims

The legal dispute over Hormuz tolls turns on a question of treaty law that has no clean resolution.

Under the United Nations Convention on the Law of the Sea (UNCLOS), all vessels enjoy a right of "transit passage" through international straits — passage that cannot be suspended, impeded, or charged for by bordering states [14]. UNCLOS Article 26 states explicitly: "No charge may be levied upon foreign ships by reason only of their passage through the territorial sea" [15]. The International Maritime Organization's secretary-general stated in April that "countries do not have the right to introduce tolls or payments or charges on these straits" [16].

Iran's counterargument is structural. Tehran signed but never ratified UNCLOS, and neither did the United States [15]. Iran contends that transit passage — a concept that emerged from UNCLOS negotiations — is a right available only to states that ratified the treaty. Since Iran did not, it says it is governed by older law: the 1949 International Court of Justice ruling in the Corfu Channel case and the 1958 Convention on the Territorial Sea, which establish a right of "innocent passage" rather than unrestricted transit passage [15].

The distinction matters. Under innocent passage, coastal states retain broader discretion to regulate shipping, determine whether passage is "non-innocent," and enforce safety and environmental rules [15]. Iran argues this framework gives it authority to control and charge for passage through what it considers its sovereign waters.

Legal scholars are largely skeptical. Philippe Delebecque, a maritime law professor at the Sorbonne, warned that allowing tolls could trigger copycat controls in the Strait of Gibraltar, the Strait of Malacca, and other critical waterways, threatening international commerce itself [10]. Julien Raynaut of the French Association of Maritime Law argued that "not having ratified the convention doesn't give [Iran] total freedom of action in the Strait of Hormuz," since customary international law — which applies regardless of treaty ratification — also prohibits discriminatory charges on transit [10].

Iran weakens its own case by charging tolls selectively: friendly states pass free while vessels linked to the US or Israel are barred entirely. This discriminatory application likely violates even the 1958 Convention, which states that innocent passage through international straits "cannot be suspended" [15].

Sanctions Architecture: What the US Is Actually Threatening

The US sanctions toolkit against Iran's maritime sector is extensive and battle-tested. OFAC maintains the SDN list, which already includes Iranian shipping lines, front companies, and dozens of "shadow fleet" tankers that have historically evaded sanctions to export Iranian crude [3].

The legal authorities backing the new OFAC alert include:

• IEEPA: Grants the president broad power to impose economic sanctions in response to national security threats. Most Iran sanctions originate here [4].
• CISADA (2010): Targets foreign financial institutions that facilitate significant transactions with Iranian entities, including in the shipping sector [4].
• Iran Freedom and Counter-Proliferation Act (2012): Extends secondary sanctions to non-US persons involved in Iran's energy, shipping, and insurance sectors [4].
• Executive Order 13846: Specifically targets Iran's petroleum and shipping sectors, providing authority to sanction anyone who facilitates significant Iranian oil transactions [4].

The enforcement record is credible. In recent years, OFAC has sanctioned 29 shadow fleet vessels and their management firms for transporting "hundreds of millions of dollars' worth of Iranian petroleum products" [17]. The Justice Department has filed civil forfeiture complaints against $15 million in funds linked to Iranian oil shipping networks [18].

No specific compliance deadline accompanied the May 1 alert. That ambiguity is itself a form of pressure: shipping firms cannot calculate a grace period, which incentivizes immediate compliance.

The Double Bind: Commercial Shipping as Proxy Combatant

The OFAC alert creates what maritime lawyers have described as a compliance trap. Shipping companies face three options, all costly:

1. Pay the toll and risk US sanctions — losing access to dollar-denominated trade, US ports, and American insurance markets.
2. Refuse the toll and risk Iranian enforcement — facing potential seizure, harassment, or denial of passage, as Iran demonstrated with vessel seizures in 2019 and 2023.
3. Reroute around the strait entirely — adding approximately 3,500 to 4,000 nautical miles and 10 to 14 extra days per voyage via the Cape of Good Hope, at a cost of roughly $4 million in additional expenses per trip [19].

Source: Voice of Emirates / Seavantage

Data as of Apr 26, 2026CSV

War risk insurance premiums have climbed from 0.125% to between 0.2% and 0.4% of ship insurance value per transit [20]. Analysts say that even if the strait fully reopens, insurance costs could remain 20 times higher than pre-war levels for an extended period [20]. Spot freight rates on affected lanes have surged 300% to 400%, with war risk surcharges reaching $1,500 per twenty-foot equivalent unit (TEU) and emergency freight increases exceeding $3,000 per forty-foot equivalent unit (FEU) [20].

The practical effect is that the US is using its financial dominance to pressure private companies into refusing Iranian authority — a strategy that critics argue outsources what should be a military or diplomatic confrontation to commercial actors. Iran controls the waterway physically; the United States controls the financial system through which shipping operates. The shipping firms are caught between the two.

The Major Importers: China, India, and the Gulf States

The countries most exposed to this standoff are those that depend on oil transiting Hormuz — and that have the most complicated relationships with both Washington and Tehran.

China purchases approximately 80% of Iran's oil exports and already conducts business with Tehran in yuan [11]. Beijing has pressed Iran to keep Hormuz open, with Foreign Minister Wang Yi telling his Iranian counterpart that Tehran should heed the "reasonable concerns" of its neighbors [21]. But China and Russia vetoed a UN Security Council resolution proposed by Bahrain in early April that would have condemned Iran's closure, calling it biased [21]. Chinese vessels have been among those transiting under Iran's toll system, and the use of yuan payments for tolls fits Tehran's broader strategy to circumvent dollar-denominated sanctions [9].

India resumed purchases of Iranian oil and gas in April 2026 after a seven-year hiatus, having secured safe passage for its ships through bilateral negotiations with Tehran [21]. Indian refiners have simultaneously diversified, securing US sanctions waivers for Russian crude and ramping imports to approximately 2 million barrels per day from alternative sources including West Africa and Latin America [21]. India's willingness to engage directly with Iran's transit system puts it in potential conflict with the new OFAC alert.

Gulf states — particularly Saudi Arabia and the UAE — are caught in a different bind. Their oil exports have historically relied on Hormuz, though Saudi Arabia has pipeline alternatives via the Red Sea. Saudi Arabia has explicitly called for keeping the strait open "without any restrictions" [10]. The UAE, closer to the conflict zone, faces elevated insurance and security costs.

The Price Tag: What Rerouting Costs the Global Economy

The disruption's economic footprint is vast. Crude oil prices surged from roughly $70 per barrel before the war to an average of $103 per barrel in March 2026 [22]. A brief drop of 11% followed the April ceasefire announcement, but prices rebounded after Iran re-closed the strait on April 18 in response to the continued US naval blockade [22].

The US imposed its own naval blockade on April 13, preventing Iranian tankers from departing and creating what analysts call a "dual blockade" — Iran controls northbound commercial traffic, while the US blocks southbound Iranian exports [22]. The US Central Command reported that 45 commercial ships had been ordered to turn around since the blockade began [1].

More than 170 million barrels of oil remained stranded in tankers across the region as of late April [13]. Commercial transits through the strait dropped by 95% [20]. The Panama Canal and Cape of Good Hope route have absorbed some of the diverted traffic, but at steep cost: an additional $4 million per voyage and 10 to 14 days of transit time [19].

For global consumers, these costs are passed through in higher fuel prices, elevated goods prices, and supply chain delays. Port congestion at alternative hubs like Mundra, India has produced delays of up to 49 days [20].

What Comes Next

The OFAC alert arrives at a moment of deadlock. Iran has offered to reopen the strait if the US lifts its naval blockade; the US has said it will maintain the blockade until Iran agrees to nuclear negotiations [22]. President Trump stated on April 30 that Iran's current peace proposals are insufficient: "They want to make a deal, I'm not satisfied with it" [2].

The toll system, whatever its legal merits, has given Iran an additional bargaining chip — and a potential revenue stream that could partially offset the losses from the US oil export blockade. The US sanctions threat is designed to strip that chip away by making compliance with Iranian tolls financially ruinous for any firm that touches the American financial system.

Whether that pressure succeeds depends on the choices of the world's largest oil importers. China's willingness to transact in yuan, India's bilateral deals with Tehran, and the broader pattern of sanctions fatigue among major economies all suggest that OFAC's reach, while formidable, may not be absolute. The shipping industry, meanwhile, is left to calculate which sovereign power poses the greater threat to its bottom line — the one that controls the water, or the one that controls the money.