For roughly two weeks, the Karachi, a Pakistani-flagged Aframax tanker loaded with crude at Das Island in Abu Dhabi, sat waiting for a signal that never came through official channels. When it finally moved, it did not take the standard shipping lane.
It hugged the Iranian coast, threading through the narrow gap between the islands of Larak and Qeshm, a route mariners are normally advised against, before tracking out into the Gulf of Oman. The tanker’s AIS transponder was broadcasting throughout, as if Tehran wanted the world to watch. The message was unmistakable: Iran was not simply closing the Strait of Hormuz. It was deciding, vessel by vessel, who had earned the right to pass.
Since Operation Epic Fury began on February 28, just 21 tankers have transited the strait, according to S&P Global Market Intelligence, compared with more than 100 ships daily before the conflict. The strait typically handles 21 million barrels of oil per day during normal operations, according to the IEA’s March 2026 assessment.
By this month, global oil supply had fallen by approximately 8 million barrels per day — a reduction the IEA has characterized as the largest oil supply disruption in history. Brent crude surged above $119 a barrel on March 19, the morning after Iran struck Qatar’s Ras Laffan gas field, before settling back above $105 at week’s end, more than 40 percent higher than before the war began.
What is emerging from the wreckage of normal transit is something more strategically dangerous than a closed strait: a permission economy, run entirely out of Tehran.
On March 5, the IRGC announced that Iran would keep the strait closed only to ships from the United States, Israel, and their Western allies. The declaration formalized what ship-tracking data had already begun to reveal. Yet, a growing number of ships have been rerouting via Iran’s territorial waters, suggesting Tehran is allowing permission-based transits to friendly nations, Iran’s Foreign Minister Abbas Araghchi confirmed the architecture in plain terms, saying the strait was “open, but closed to our enemies” — a formulation he repeated across multiple statements that week as Iran’s selective passage policy hardened into a deliberate framework.
According to a United States intelligence source, speaking to The Cipher Brief on background, the process is more transactional than diplomatic: a vessel requests permission directly from the IRGC, and if clearance is granted, it passes missile and drone-free. Those permissions, the source said, come at a price: vessels must pay a fee for the privilege of passage.
The beneficiaries have been carefully chosen.
Iran’s ambassador to India, Mohammad Fathali, confirmed that Tehran had allowed some Indian vessels to pass. Two Indian-flagged tankers carrying liquefied petroleum gas bound for ports in western India crossed early one morning, according to Rajesh Kumar Sinha, special secretary at India’s Ministry of Ports, Shipping and Waterways.
A Turkish-owned ship was also allowed to transit after Ankara received permission from Tehran; earlier, the Panama-flagged but Turkish-owned LPG tanker Bogazici had broadcast via AIS that it was a Muslim vessel under Turkish operation before successfully crossing.
Moreover, Pakistan’s passage was confirmed through a combination of Iranian clearance and direct naval coordination. A military source told Reuters that Pakistani naval officials had been in contact with Iranian counterparts. “No escort was needed, being Pakistani vessels,” the source said. The Pakistan Navy nonetheless provided maritime security to the vessel throughout its journey, according to Pakistan’s Express Tribune.
Jim Krane, energy research fellow at Rice University’s Baker Institute, tells The Cipher Brief that Iran is taking a page directly out of the Houthis’ playbook.
“They’re using Hormuz restrictions as a form of targeted economic sanctions on countries and firms with links to the U.S. and Israel,” he says. The Houthis did the same thing in the Bab al-Mandeb and the Red Sea. ‘Friendly’ cargoes were allowed to proceed, and those with connections to Israel, the United States, and Europe were denied passage.”
The logic is deliberate. Turkey is a NATO member but has maintained independent ties to Tehran. India has not joined any coalition against Iran and continues to import significant volumes of Iranian crude. China, which receives around 45 percent of its oil imports via the strait, was the first country Iran signaled it would favor, with reports emerging on March 4 that Tehran would initially allow only Chinese vessels to pass, citing Beijing’s supportive stance since the conflict began.
The architecture of the selective passage
The vessels that have made it through have not had an easy transit. Even routes shadowing the Iranian coast carry risk. On March 12, a China-owned container vessel called Source Blessing, operating under the Hapag-Lloyd and Maersk Gemini Alliance and broadcasting “China Owner” via AIS, was struck by falling debris while sailing toward Jebel Ali in the United Arab Emirates — not in the strait itself, but close enough to unsettle Chinese shipowners who have since largely avoided the route, according to Lloyd’s List Intelligence.
The attacks have followed no discernible pattern, making planning nearly impossible because operators cannot determine the rationale for targeting one ship rather than another. On March 11, a Thai-flagged bulk carrier, the Mayuree Naree, was struck by two projectiles while transiting the strait, setting fire to the engine room and forcing 20 of its 23 crew to abandon ship. Three crew members remained missing and believed trapped below. By March 6, the IMO Secretary-General confirmed at least six seafarers had lost their lives in attacks on vessels since the war began.
GPS and AIS interference has intensified sharply, affecting more than 1,650 vessels as of March 7 and concentrating spoofed positions near Fujairah and the Gulf of Oman, according to Windward. Some captains have gone dark deliberately — India’s maritime fusion center noted a rise in vessels conducting “dark transits” with AIS disabled to obscure their positions.
Roughly 400 vessels were spotted in the Gulf of Oman, a massive backlog waiting near the chokepoint, according to satellite intelligence from mid-March. About 22 vessels carrying crude, LPG, and liquefied natural gas remained anchored in the strait itself, awaiting confirmation of safe passage.
Skip York, a nonresident fellow at Rice University’s Baker Institute for Public Policy, tells The Cipher Brief that Iran’s closure is ultimately a one-time card.
“It works in the short-term because there are no easy bypass options for all Gulf exports, especially LNG,” he says, but stresses that it accelerates the very supply diversification it seeks to prevent and “runs the risk that shipments out of the Gulf can be seen as unreliable — thus encouraging diversification to oil and gas supplies from other regions.”
Krane is blunter about the path back to open transit.
“Hard to see the U.S. and Israelis bombing their way to an open strait,” he underscores. “Either we invade Iran with ground troops, or we call off the war.”
A fracturing coalition response
The military pressure campaign escalated sharply on March 19, when Joint Chiefs Chairman Gen. Dan Caine announced at a Pentagon press briefing that A-10 Warthog aircraft had entered the fight. “The A-10 Warthog is now in the fight across the southern flank and is hunting and killing fast-attack watercraft in the Straits of Hormuz,” Caine said, adding that AH-64 Apache helicopters from both American forces and regional allies had joined to handle Iranian one-way attack drones.
United States Central Command subsequently published footage of American strikes destroying Iranian naval assets threatening international shipping in and near the strait. Iran, despite the sustained pressure, retains significant asymmetric capabilities — mobile missile launchers, drones, and small boats that can be rapidly deployed from hidden coastal bases.
The coalition picture, meanwhile, remained fractured. At an EU summit in Brussels on March 19, European leaders doubled down on their refusal to join the American and Israeli military campaigns. EU foreign policy chief Kaja Kallas had made clear days earlier that there was “no appetite” among member states to expand the Aspides naval mission from the Red Sea to the Strait of Hormuz, and the summit produced no change in that position.
Germany’s Chancellor Friedrich Merz drew a clear line at the Brussels summit, saying his country would engage only after hostilities ceased.
“We can and will commit ourselves only when the weapons fall silent,” Merz said of potential German military support to secure shipping lanes in the Strait of Hormuz. “We can then do a great deal, up to opening sea lanes and keeping them clear, but we’re not doing it during ongoing combat operations.”
France, Germany, Italy, the Netherlands, the United Kingdom, and Japan issued a joint statement calling on Iran to “cease immediately” its drone and missile attacks and its other attempts to block the strait and expressing readiness to “contribute to appropriate efforts” to ensure safe passage — but stopping well short of deploying combat assets. NATO Secretary General Mark Rutte, meanwhile, acknowledged the urgency without offering specifics.
“Everybody agrees this strait cannot stay closed. It has to open up again as soon as possible. This is crucial for the world’s economy,” Rutte said. “I am confident that allies, as always, will do everything in support of our shared interests. So we will find a way forward.”
York’s near-term menu is narrow. Military pressure is one option, but he sees mediators as the more realistic path. Before Iran struck Ras Laffan on March 18, Qatar’s foreign ministry had said communications with different parties were ongoing — though Doha drew a hard line: no formal talks until Iran stopped attacking its neighbors.
Nothing like the broad convoy operations of the 1980s Tanker Wars — something tighter, more selective, and politically viable given how few allies have been willing to show up.
Read one way, Tehran’s approvals are nothing more than pure coercion. Read another, they are the unwritten beginnings of a framework, terms that exist in practice before anyone has put them on paper.
“This is in many ways positive news, as it indicates that Iran recognizes the need to allow shipping through and that it is open to such negotiations,” Christian Bueger, a maritime security scholar at the University of Copenhagen and the United Nations Institute for Disarmament Research, tells The Cipher Brief, adding that it could “potentially open up possibilities for a more structured and effective approach, initially only for a number of states.”
Moving from passage-by-passage to a rules-based system, he argues, would require “a sort of clearinghouse and coordination mechanism that also involves the shipping industry.”
The yuan gambit and what comes next
Reports have emerged that Iranian authorities floated the idea of allowing limited tanker traffic on the condition that oil transactions be conducted in Chinese yuan. Analysts are split on how much it matters. York’s view is that the dollar’s grip on global energy markets is structural, not symbolic.
“Chinese bond markets are relatively closed, yuan convertibility is restricted, and hedging instruments are thin compared to dollar markets,” he points out.
Krane, however, is similarly skeptical, observing that Iran already settles oil exports in yuan and that it is “not a major share of the market.”
Bueger frames it differently — as deliberate provocation rather than viable policy, “an attempt to undermine U.S. dollar centrality” that Iran will ultimately struggle to enforce.
The math is brutal. More than 75 percent of global spare production capacity is in Middle Eastern countries that ship through the strait, blunting whatever relief emergency reserves can offer. The IEA’s release of 400 million barrels, the largest in its history, covers roughly 20 days of normal Hormuz flows at best.
Under new Supreme Leader Mojtaba Khamenei, the strait continues to serve as Iran’s primary lever. As recently as March 20, he issued a written statement declaring that the “security” of Iran’s enemies “must be taken away” — a formulation that left the definition of enemy, as always, entirely to Tehran. The permission-economy Iran is now running is not a crisis to be managed in the short term, so much as a new geopolitical architecture being stress-tested in real time.
“The war with Iran is so unpopular globally that the sanctions strategy might work, because it allows opponents of the war to signal their displeasure with the U.S. and Israel,” Krane adds. “The countries that get rewarded are the ones willing to make small concessions to Iran — and in return, they gain access to important cargoes via the strait.”
The Cipher Brief is committed to publishing a range of perspectives on national security issues submitted by deeply experienced national security professionals. Opinions expressed are those of the author and do not represent the views or opinions of The Cipher Brief.
Have a perspective to share based on your experience in the national security field? Send it to Editor@thecipherbrief.com for publication consideration.
Read more expert-driven national security insights, perspective and analysis in The Cipher Brief
