U.S. Threatens Sanctions on Shippers Paying Iran Strait Tolls as Peace Talks Collapse

The Trump administration threatened secondary sanctions on Friday against shipping firms paying Iranian tolls for Strait of Hormuz passage, hours after President Trump rejected Tehran’s latest peace proposal. The Office of Foreign Assets Control warned both U.S. and foreign companies they risk sanctions exposure for payments to Iran or the Islamic Revolutionary Guard Corps, a move that extends U.S. enforcement leverage over the 20% of global oil flows that normally transit the strait.

Trump dismissed Iran’s offer to reopen the strait and lift the U.S. naval blockade in exchange for ending the war and postponing nuclear talks. “They want to make a deal, I’m not satisfied with it, so we’ll see what happens,” he told reporters, according to The Boston Globe. The rejection signals the administration’s intent to use Strait access as a negotiating instrument rather than accept a phased settlement.

Toll Payment Mechanism and Enforcement Scope

Iran began charging transit fees exceeding $1 million per vessel after the April 8 ceasefire, with some ships paying up to $2 million to pass through the strait, per The Hill. The OFAC alert warns that payments made via fiat currency, digital assets, or in-kind transfers all carry Sanctions risk. “OFAC is issuing this alert to warn U.S. and non-U.S. persons about the sanctions risks of making these payments to, or soliciting guarantees from, the Iranian regime for safe passage,” the agency stated in its official advisory.

The warning extends the administration’s “maximum pressure” campaign, which has designated over 1,000 Iranian-related persons, vessels, and aircraft since February 2025. On April 24, Treasury sanctioned 40 Shipping firms and Hengli Petrochemical, a major Chinese refinery, for Iran trade. Treasury Secretary Scott Bessent has explicitly warned financial institutions in China, Hong Kong, the UAE, and Oman of secondary sanctions if they maintain business ties to Tehran.

Shipping Cost Inflation and Insurance Fragmentation

War-risk insurance premiums for Strait transits have surged from a pre-war baseline of 0.125% of hull value to 2-6% as of mid-April, according to IBTimes. For a Very Large Crude Carrier worth $100 million, current insurance costs range from $200,000 to $360,000 per voyage. Peak rates in March reached $2-3 million per single transit — a 400-4,000% increase from baseline.

The U.S. government has intervened directly in shipping risk markets. The International Development Finance Corporation now provides up to $40 billion in political risk insurance reinsurance on a rolling basis for Hormuz transits, per the World Economic Forum. The facility marks a shift toward government-backed insurance of last resort as private underwriters withdraw from Iran-adjacent routes.

Supply Disruption and Price Dynamics

Strait of Hormuz traffic collapsed from 3,000 vessels per month pre-war to 154 in March — a 95% reduction, according to CNN citing Kpler data. Supply from the strait, which normally handles 20 million barrels per day, has fallen to approximately 1 million barrels per day. Brent crude closed at $114.01 on April 30 after an intraday surge to $126, per CNBC. Prices have climbed 60% since the conflict began.

The U.S. Energy Information Administration forecasts Brent will peak at $115 per barrel in Q2 2026 before easing, with the Brent-WTI spread reaching $15 in April when disruptions were largest. “The oil market has moved from over-optimism to the reality of the supply disruption we are seeing in the Persian Gulf,” Warren Patterson, head of commodities strategy at ING, told CNBC. “The longer this disruption persists, the less the market can rely on inventory, and the greater the need for further demand destruction.”

Precedent for Sanctions Leverage Over Global Commerce

The OFAC alert establishes secondary sanctions risk for any entity facilitating Iranian revenue from Strait passage, regardless of nationality. Foreign financial institutions that process toll payments face potential designation under the administration’s “Economic Fury” campaign. This extends U.S. enforcement reach beyond traditional sanctions targets to routine maritime commerce, effectively requiring global shipping firms to choose between Strait access and access to U.S. financial systems.

The move follows a pattern of escalating third-party sanctions. Treasury has already warned institutions in China, Hong Kong, the UAE, and Oman — jurisdictions that handle significant Iran-related financial flows — of secondary sanctions exposure. The April 24 designation of Hengli Petrochemical, a major Chinese refiner, marked the first time the administration sanctioned a large-scale downstream buyer of Iranian crude.

What to Watch

Monitor whether major shipping firms publicly announce Strait transit suspensions or route diversifications in response to the OFAC warning. The Baltic Dirty Tanker Index, which tracks crude shipping costs, will signal whether insurance and compliance costs are accelerating beyond current 2-6% premiums. Any Iranian retaliation via vessel interdiction or harassment would likely push Brent above the EIA’s $115 forecast ceiling.

Watch for secondary sanctions designations targeting financial institutions processing toll payments, particularly in Chinese and UAE banking sectors. The administration’s willingness to sanction Hengli Petrochemical suggests a higher tolerance for disrupting third-country energy supply chains than previous enforcement cycles. Finally, track whether the DFC’s $40 billion reinsurance facility sees increased uptake — a sign that private underwriters are exiting Iran-adjacent routes entirely, forcing permanent government backstopping of Persian Gulf shipping risk.