The double Iranian and American blockade imposed on the Strait of Hormuz, one of the world’s main hydrocarbon supply routes, has turned its transit into a cat-and-mouse game in which ships challenge the limits using irregular tactics and diversion maneuvers to take advantage of exceptions, but it has also caused some vessels to interrupt their voyage and turn back to avoid confrontations that could endanger negotiations hanging by a thread and the fragile ceasefire in place.
Read more Trump puts a veteran military doctor in charge of the health prevention agency in the US
While the Iranian blockade of Hormuz focuses on the narrowest part of this maritime route — about 35 kilometers wide — the American one is located further east, at the exit of the Gulf of Oman to the Indian Ocean, a space about 300 kilometers from north to south. A dozen US military vessels, including the aircraft carrier USS Abraham Lincoln, and numerous aircraft have been deployed in these waters to enforce the blockade, which came into effect on Monday.
Every afternoon, the United States Central Command publishes the results of its mission, emphasizing that no vessel has crossed its barrier. “After 72 hours of enforcement, 14 ships have turned back to comply with the blockade at the direction of US forces,” it posted on the social network X on Thursday.
Among those that changed course is the Rich Starry, a Chinese-owned ship loaded with 250,000 barrels of methanol and sanctioned by the United States, which was the first to cross Hormuz after the US blockade was implemented. However, it turned around in the Gulf of Oman and on Thursday was anchored off the Iranian island of Qeshm, again within the strait, according to MarineTraffic data.
“Merchant ships have continued to cross the Strait of Hormuz using routes closer to Iran, suggesting that Iran’s approval mechanism remains in effect. The US naval stance seems focused on a distancing blockade, aiming to restrict traffic to and from Iranian ports without completely closing the strait,” explains Daniel Mueller, senior analyst at maritime risk management company Ambrey, in statements to EL PAÍS.
A report from maritime intelligence company Windward stated that during the first 48 hours of the naval blockade, 19 ships crossed the Strait of Hormuz, five heading to the Persian Gulf and 14 to the Gulf of Oman, including at least two tankers and five cargo ships flying the Iranian flag, although it is unclear if they reached Indian Ocean waters.
On Thursday, Bloomberg reported the passage through Hormuz of two other ships sanctioned by the United States and linked to Iran. “Ships have been observed transiting the strait towards Iran, with some changing their destination port to hide that they will dock at Iranian ports,” explains the specialized publication Lloyd’s List.
The rules of the blockade are not entirely clear and, in several statements, the United States says that “neutral” ships are allowed to continue sailing. But on Thursday, its forces issued a Navtex — a telegraphic alert to ships and ports in the area — in which they added that, in addition to Iranian ships, the US fleet will “board” for inspection and even seizure any vessel subject to US sanctions or suspected of “smuggling,” which includes any type of hydrocarbons.
Read more Wildfires in Mexico increase in 2026
This situation is driving the use of diversion maneuvers, notes the Windward report. International maritime regulations require large-tonnage and size ships to always keep their transponder on, a device that communicates with the Automatic Identification System (AIS) and transmits the ship’s name, position, route, and other details.
Recently, especially following the Russian invasion of Ukraine, maneuvers such as keeping AIS communication off (something only allowed in certain risk situations) have proliferated to avoid detection or hide the ports where a particular vessel docks, which has led to ships abusing these illegal tactics being called ghost fleet or dark fleet.
There are other methods such as spoofing, which consists of altering the information transmitted to the AIS, for example, the ship’s position, identification number, or navigation history. This creates “navigation hazards, especially in such congested waterways” and “increases the possibility of collisions,” explains Mueller. Moreover, it increases risks for the various regulatory layers involved in each maritime shipment (shipowners, vessel owners, freight and vessel insurers, maritime agents…) by “undermining transparency” and “complicating due diligence processes.”
“Zombie ships”
A variant of spoofing is the tactic called “zombie ship,” in which the identity of another vessel, often retired from service, is transmitted, something that has been detected several times in the Strait of Hormuz. This is the case of the tanker using the identification Race — a ship that was scrapped more than a decade ago — and which, after having passed the blockade, is currently heading towards India. Its signal indicates it loaded at the Iraqi port of Basra, although Lloyd’s List believes its cargo is Iranian, although it is unclear whether loaded directly at a port in the Islamic Republic or through a ship-to-ship transfer operation.
“For years, increasingly sophisticated efforts have been made to hide voyages to Iranian ports. Tankers from clandestine fleets often emit false AIS positions placing them in non-Iranian Middle Eastern ports to hide that they are actually loading Iranian product,” the shipping publication states, citing a recent analysis estimating that “approximately half” of the declared stops at the Iraqi port of Khor al Zubair, near the border with Iran, are false and used to mask the loading of Iranian crude or gas.
The Ambrey analyst notes that these tactics have been observed since the start of the conflict but clarifies that “although they make remote tracking” of ships “more difficult,” they “do not prevent detection by radar or physical interception.” The US deployment includes several reconnaissance aircraft, along with the use of optical radars and devices for capturing radio signals and even mobile phone signals from sailors on board, which may limit the effectiveness of distraction tactics by ships attempting to evade the blockade. In fact, the US Chief of Staff, Dan Caine, warned ghost ships and those violating international navigation regulations in the blockade zone that they risk being boarded by his fleet.
