Shipowners are rushing to understand the fine print of a US-Iran ceasefire that could temporarily unblock the Strait of Hormuz and open an exit for more than 800 vessels trapped in the Persian Gulf.

The vital waterway has been virtually closed since US and Israeli strikes at the end of February prompted Iran to tighten its control, triggering an unprecedented energy-supply crunch. Unable to guarantee the safety of thousands of seafarers and their cargoes, vessels have instead been loitering on either side, and traffic has slowed to a trickle.

Then, hours before a deadline set by President Donald Trump ran out during the US evening on Tuesday, the two sides agreed a ceasefire in exchange for a reopening. 

Key details remain uncertain: Iran says it has agreed to two weeks of safe passage in coordination with its armed forces and within “technical limitations”, while Trump announced a “COMPLETE, IMMEDIATE, and SAFE OPENING”. It is also unclear if the two have settled on transit payments, or when the truce takes effect.

Trump said in a separate social media post that the US would be “helping with the traffic build up” and “hangin’ around” to ensure smooth flows.

For shipowners, however, the initial news has been enough to prompt tentative optimism. The Japanese Shipowners’ Association, a major industry group, was among those which said it would check the details of the US-Iran agreement, and then relay information to members. 

Most, however, warned that more clarity would be required for ships to move, and even in the best case flows would take time to resume in earnest. In peacetime, some 135 ships transit daily, a figure that has shrunk dramatically.

“You don’t switch global shipping flows back on in 24 hours,” said Jennifer Parker, adjunct professor at the University of Western Australia Defence and Security Institute. “Tanker owners, insurers and crews need to believe the risk has actually reduced — not just paused.”

Ships that transport energy make up a large part of the fleet that’s stuck inside the gulf, data from Kpler show. There are currently 426 tankers hauling crude oil and clean fuels, plus 34 liquefied petroleum gas carriers and 19 liquefied natural gas vessels. The remainder are carrying dry commodities, like agricultural or metal products, or containers.

Ceasefire plans are a necessary step, but only an initial one, said Lewis Hart, head of marine in Asia at insurance broker Willis Towers Watson. “Even within a two‑week window, we expect activity to restart in a measured manner rather than all at once,” he said.

Traders and shipowners will now be closely monitoring which ships start making their way to transit the strait in either direction — especially those that would not normally have Iranian protection — and how they fare. As of Wednesday morning, more than 1,000 vessels are waiting on both sides in clusters around Dubai and Khor Fakkan.

“It’s good to see that the market is reacting the way it is, but this is day one of a tentative ceasefire,” Michael Pregent, a former US Intelligence advisor, told Bloomberg Television. “We are likely to see the regime control who moves through, who is charged what, and who is denied.”

The first two ships to attempt an exit since the announcement appear to be sailing as a pair toward Iran’s Larak and Qeshm islands on Wednesday morning, ship-tracking data show. One of them is the Tour 2, a US-sanctioned Suezmax that’s flagged to Iran. 

Sailing next to the tanker is a Greek-owned bulk carrier, NJ Earth, whose voyage history within the Persian Gulf suggests either spoofing to hide location or interference by electronic warfare. There were no contact details listed on database Equasis for its owner, NJ Earth Marine Ltd., and manager, NJ Trust Marine Ltd. 

Movement of LNG ships will also be particularly closely monitored, as no loaded carrier has made it through the strait since the war began and one recent attempted transit ended in a last-minute U-turn. About 20% of global LNG traffic went through Hormuz last year.

According to an International Maritime Organization tally at end March, some 20,000 civilian seafarers are stuck onboard these ships and the other utility and support vessels. Those crew members have been facing dwindling supplies, fatigue and psychological stress, the United Nations agency warned.

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Published on April 8, 2026