Shipping Freeze Deepens in Strait of Hormuz

Traffic through the Strait of Hormuz remained largely frozen amid increasing tensions, as Iran attacked ships and the US started a plan to guide vessels out of the vital waterway.

Activity was limited to a handful of vessels, mostly linked to Iran, as of early afternoon in London on Monday. US President Donald Trump’s proposal to help stranded ships out of the Persian Gulf, framed as a “humanitarian gesture,” left shipping executives looking for details as the security outlook remains uncertain.

Meanwhile, US Central Command said on X that two American-flagged merchant vessels successfully navigated the strait, noting that the military is actively working to restore commercial flow. There were 5 US flagged commercial vessels in the Persian Gulf at the end of February, but none of them have turned on their Automatic Identification System signal for weeks. 

The latest US plan comes after days of stalemate over Hormuz transits and the wider war in the Middle East. Millions of barrels of oil and other products are stuck inside the Persian Gulf as Iran attempts to tighten its grip on the chokepoint. The country’s semi-official Tasnim news agency reported on Monday an expanded control zone across the strait, stretching as far as the borders with the United Arab Emirates.

Recent ship movements underscore the uncertainty. Early Monday, a Panama-flagged bulk carrier and two Chinese-owned vessels abandoned outbound voyages toward the strait and turned west. The diversions coincided with a UKMTO alert warning of unidentified radio commands instructing ships to clear the area, highlighting the region’s unpredictable risks.

Commercial traffic on Monday morning remained sparse. Vessel-tracking data show just two transits: an Iran-linked liquefied petroleum gas carrier exiting the Gulf and an India-linked regional feeder containership entering.

Iranian media suggested that Tehran has expanded its defined control zone across the strait, from south of Mount Mobarak to Fujairah, and from west of Qeshm Island to Umm al Quwain. The move further complicates navigation in one of the world’s most critical waterways.

Ship Movements

The subdued activity follows an equally slow Sunday, when only one bulk carrier took the outbound route alongside a handful of smaller regional vessels, including three small cargo ships and a bitumen carrier.

Ships transiting Hormuz with active AIS signals over the past day were confined to the narrow northern lane approved by Tehran.

Recent Iran-linked departures have largely stalled in the Gulf of Oman. It remains unclear whether these vessels are following regional trading patterns or are being held up by a US naval blockade  positioned further east.

The Indian containership’s Monday entry into the Persian Gulf follows the arrival of an Iran-linked LPG vessel and a bulk carrier a day earlier.

The US presence may also be distorting the traffic picture. Iran-linked vessels entering or leaving the Gulf could be switching off AIS signals to avoid detection, making it harder to track flows in real time. As a result, transit counts may later be revised upward when ships reappear further from high-risk waters.

Even before the latest US restrictions, it was common for Iran-linked vessels to go dark when approaching Hormuz. Signals were often not restored until well into the Strait of Malacca—around 13 days’ sailing from Iran’s Kharg Island.

NOTES: 

Because vessels can move without transmitting their location until they’re well away from Hormuz, automated positioning signals were compiled over a large area covering the Gulf of Oman, the Arabian Sea and the Red Sea to detect those that may have departed or entered the Persian Gulf.

When potential transits are identified, signal histories are examined to determine whether the movement appears genuine or is the result of spoofing — where electronic interference can falsify the apparent position of a ship. 

Some transits may not have been detected if vessels’ transponders haven’t been switched back on. Iran-linked oil tankers often steam from the Persian Gulf without broadcasting signals until they reach the Strait of Malacca about 10 days after passing Fujairah in the UAE. Other ships may be adopting similar tactics and won’t show up on tracking screens for many days.

This tracker will be published during heightened tensions involving Iran, and aims to capture traffic for all classes of commercial shipping.