Japan Breaks Hormuz Blockade with Two Tanker Transits, Testing Iran’s Toll Regime
Diplomatic coordination secures 3.9 million barrels of Gulf crude, signaling Tehran's shift from closure to revenue extraction as regional supply routes stabilize.
Japan has successfully navigated two oil tankers carrying 3.9 million barrels of crude through the Strait of Hormuz since May 1, marking the first major breach of Iran’s three-month blockade and establishing a diplomatic template for restoring Persian Gulf shipping flows.
The breakthrough began April 29 when the Idemitsu Maru, a Panamanian-flagged very large crude carrier (VLCC), exited the Strait with 2 million barrels of Saudi crude bound for Nagoya. The vessel followed a Tehran-approved northern route near Qeshm and Larak islands, according to Newsweek. A second Japanese-managed tanker operated by Eneos cleared the waterway May 6-7 carrying 1.2 million barrels of Kuwaiti crude and 700,000 barrels from the UAE, per OilPrice.com citing vessel tracking data.
The transits represent the first significant commercial traffic through the chokepoint since Iran declared the Strait effectively closed February 28 following U.S.-Israeli strikes that killed Supreme Leader Ali Khamenei. Monthly vessel counts collapsed from approximately 3,000 before the conflict to just 191 in April, with near-zero open transits recorded in early May, according to CNN analysis of tracking data.
Diplomatic Coordination Over Military Confrontation
Japan’s success reflects months of direct engagement between Prime Minister Sanae Takaichi and Iranian President Masoud Pezeshkian. The Idemitsu Maru had been stranded in UAE waters since loading at Saudi Arabia’s Juaymah terminal in early March, waiting weeks for clearance, The Japan Times reported.
“Our country has, to date, made representations to Iran on every possible occasion, from the standpoint that it is important to ensure the early restoration of free and safe navigation through the Strait of Hormuz for vessels of all countries, including Japan.”
— Prime Minister Sanae Takaichi
The diplomatic breakthrough coincided with Iran’s establishment of the Persian Gulf Strait Authority on May 5, which requires ship owners to coordinate transits via email and obtain Iranian clearance. The framework represents a shift from outright closure to controlled access with implicit tolling, according to Al Jazeera reporting on the new regulations. Tehran is also negotiating a permanent framework with Oman to formalize the revenue system.
Japan secured approximately 60% of its crude oil needs in May from sources bypassing the Strait while covering the shortfall with U.S. imports, per Newsweek. The country depends on the Middle East for roughly 95% of crude imports, with 70% normally transiting Hormuz before the conflict.
Insurance Costs Remain Prohibitive for Most Operators
War-risk insurance premiums surged from 0.02-0.125% of vessel value pre-conflict to 0.5-1% or higher by March, translating to $600,000-$1.2 million per transit for a $120 million tanker compared to $40,000 previously. The 2,000% increase renders most commercial voyages economically unviable, according to House of Saud analysis of underwriter quotes.
| Factor | Pre-Conflict | Post-February 28 |
|---|---|---|
| War-risk premium | 0.02-0.125% | 0.5-1%+ |
| Cost per $120M VLCC | $24k-$150k | $600k-$1.2M |
| Monthly Hormuz transits | ~3,000 | 191 (April) |
| Stranded Gulf vessels | 0 | 800+ |
The second Japanese vessel operated with its transponder off during transit, suggesting continued security concerns despite Iranian clearance. More than 800 vessels remain stranded in Gulf waters, with owners awaiting either insurance repricing or clearer diplomatic protocols before attempting passage.
Market Response and Supply Chain Implications
Brent crude traded at $104.52 per barrel as of May 22, up 1.89% from the previous day and 61.35% higher than a year prior, according to Trading Economics. The U.S. withdrew nearly 10 million barrels from the Strategic Petroleum Reserve in the week of May 13-20, marking the largest weekly release on record as Washington attempts to moderate prices.
Middle East producers collectively shut in 10.5 million barrels per day in April across Iraq, Saudi Arabia, Kuwait, the UAE, Qatar, and Bahrain, per the U.S. Energy Information Administration. The agency had forecast Hormuz remaining closed through late May, but actual transits now challenge that assumption.
The Strait of Hormuz handles roughly 21% of global petroleum liquids consumption in normal conditions. Iran’s selective tolling approach mirrors revenue tactics during the 1980s Tanker War, when Tehran imposed de facto transit fees through selective attacks rather than complete closure. The current framework allows Iran to extract economic value while avoiding the total supply cutoff that would guarantee sustained Western military intervention.
Trump Rejects Iranian Framework
President Donald Trump dismissed Iran’s tolling regime on Truth Social, stating that Iran had informed the U.S. it is in a “State of Collapse” and wants Washington to “Open the Hormuz Strait” as Tehran tries to “figure out their leadership situation,” according to Newsweek. The statement suggests Washington sees the tolling system as evidence of Iranian weakness rather than a sustainable framework.
United Against Nuclear Iran (UANI) has tracked at least 70 Iranian oil loadings since the conflict began, representing approximately 82 million barrels and generating over $6 billion in estimated revenue for the Islamic Revolutionary Guard Corps. The figures indicate Iran has maintained substantial export volumes despite the Strait restrictions, using alternative routes and covert shipping networks.
What to Watch
Insurance underwriters will reprice war-risk premiums in coming weeks as transit patterns stabilize or deteriorate. A sustained flow of Japanese vessels under Tehran’s coordination framework could establish a template for European and Asian buyers, gradually restoring commercial traffic. However, the system’s viability depends on Iran maintaining selective enforcement rather than reverting to broader attacks.
Watch whether other major importers — South Korea, China, India — secure similar diplomatic clearances or whether Japan’s success reflects unique bilateral positioning. The divergence between Trump’s rejection of the tolling framework and Japan’s pragmatic engagement suggests competing Western strategies that could complicate broader Strait normalization. Oil prices will signal market confidence: sustained trading above $100 per barrel indicates expectations of continued supply disruption, while a slide toward $90 would reflect growing confidence in access restoration.