Despite escalating tensions in the Strait of Hormuz, a small number of commercial vessels are continuing to navigate the strategic waterway by employing unusual tactics and coordinating closely with the US military, according to a report by The Wall Street Journal. The report says some ships, including large crude oil and liquefied natural gas tankers, have been sailing in what the maritime industry calls “dark mode,” switching off their Automatic Identification Systems (AIS) to reduce their electronic visibility and lower the risk of being targeted by Iran.
AIS transponders are normally used by ships to broadcast their location and avoid collisions. However, turning them off makes vessels significantly harder to track electronically.
According to the Journal, shipowners and US officials said vessels transiting the strait remain in communication with American military personnel, who use radar, drones and surveillance systems to monitor traffic and provide guidance during the crossing.
The US military has reportedly advised commercial ships on when to go dark and how to respond to potential Iranian threats while passing through the narrow waterway, one of the world’s most critical oil transit routes.
A Lifeline For Global Trade
The successful passage of even a handful of vessels has provided what the report described as a “tiny relief valve” for global energy markets, which have been rattled by fears of disruption in the Gulf.
Some of these ships have reportedly used a route through the Persian Gulf that was previously secured under a US-led initiative known as “Project Freedom,” which involved naval and air escorts for commercial traffic.
Although the operation was later suspended after Iranian attacks on vessels and restrictions imposed by Saudi Arabia on US military access, the report said American forces had already helped establish a relatively safer corridor by clearing mines with underwater robotic systems.
Captain Tim Hawkins, a spokesperson for the US Central Command, told the newspaper that the military remains “continually communicating and coordinating with ships transiting the Strait of Hormuz.”
The report further noted that US forces recently destroyed Iranian mine-laying boats and struck missile and drone sites in what officials described as defensive actions aimed at protecting maritime traffic.
Greek Supertanker Breaks Through
Among the vessels that successfully transited the strait was a Greek-owned supertanker carrying approximately two million barrels of crude oil.
The tanker had reportedly remained stranded in the Persian Gulf since early March before eventually departing earlier this week. Maintaining contact with US officials, it sailed along Oman’s coastline and is now en route to India.
The Journal reported that Greek shipowners whose vessels have successfully made the crossing are now fielding requests from customers seeking similar arrangements for their cargo shipments.
Only A Handful Of Ships Making The Journey
Data from maritime intelligence firm Kpler, cited by the newspaper, showed that fewer than five vessels per day have undertaken dark transits through Hormuz since March 2.
That is a dramatic decline from normal conditions, when more than 100 ships crossed the strait daily.
Most commercial vessels continue to use the shipping lane designated by Iran along the northern side of the waterway, close to the Iranian coastline.
Traffic through the strait has repeatedly slowed or nearly halted during periods of military escalation, including recent US strikes on Iranian missile and drone infrastructure.
The report also highlighted the case of Vicstar, a Chinese-owned vessel carrying fertiliser from the United Arab Emirates to Brazil, which reportedly completed a dark transit on May 17 after spending nearly three months stranded in the Gulf.
Mounting Costs, Growing Risks
The delays are proving costly for shipping companies.
According to maritime analysts cited in the report, operators of large crude carriers incur daily expenses of between $10,000 and $15,000 on fuel, maintenance and crew costs while vessels remain idle. Insurance premiums have also surged, while crews are receiving additional compensation for operating in a war-risk zone.
Industry experts warn, however, that dark sailing comes with significant dangers.
Without AIS signals, ships cannot easily identify nearby vessels electronically and must rely heavily on radar systems and crew judgment to avoid accidents.
“There are obviously safety and security risks” associated with dark sailing, Claire Jungman, director of maritime risk and intelligence at Vortexa, told the Journal.
Insurance companies remain divided on the practice. Some charge higher premiums for vessels travelling under naval protection, arguing that military escorts could make ships more visible targets. Others offer discounts, viewing the escorts as an added layer of security.
According to the report, insurance costs for ships transiting Hormuz have surged to between 2.5% and 4% of a vessel’s value, compared with roughly 0.25% during peacetime.
Meanwhile, Iran has reportedly maintained during ongoing negotiations that it should retain a role in regulating vessel traffic through the strait and could potentially seek to impose tolls on commercial shipping, the report added.