The Eritrean government revealed today, Friday, that the oil tanker “Sebu 1,” which flies the country’s flag and appears widely as such on ship-tracking websites, is not registered with it, in an incident that sheds light on part of the operating mechanisms of the “shadow fleet” used to transport Iranian oil and circumvent American sanctions.

The tanker was hijacked off the coast of Yemen last week, and it is believed that its kidnappers changed its course towards Somalia, while the United States imposed sanctions on it last December, as it is part of the network used to transport Iranian oil products and bypass American restrictions.

The International Maritime Organization’s database showed that the tanker’s current flag status is classified as “Eritrea – Incorrect,” which means that its registration under the Eritrean flag is not recognized as valid, according to what was reported by Reuters.

The incident reveals how changing registration data or using unrecognized flags can complicate identifying the ship owner and parties associated with the shipment, as part of the methods of concealing the identity of tankers used in the sanctioned oil trade.

Over the years, Tehran has developed a complex maritime network that helps it keep its shipments moving away from international oversight and sanctions, which means that the restrictions imposed on its exports do not necessarily mean stopping the flow of crude.

The “Shadow Fleet” stands at the heart of this system, as a network of tankers, companies, and intermediaries that use multiple methods to hide the identity of ships, the source of shipments, and their routes, allowing Iranian oil to reach buyers despite American restrictions.

This network is not based on fixed carriers operating for one party. Rather, the ownership, management, and registration data of its ships change with the escalation of sanctions, and the roles of owners, operators, intermediaries, and service companies overlap.

The US Treasury Department indicates that Iranian oil smuggling networks use tankers linked to various parties, in addition to front companies and entities registered in multiple countries, making it difficult to determine the real owner or the ultimate beneficiary of the deal.

Therefore, in many cases, US sanctions target the ship, the companies that own or manage it, and the intermediaries associated with it, to gain access to the commercial network behind the shipping process, and not the carrier alone.

The US Treasury says that networks linked to Iranian oil smuggling used intentional interruptions in the transmission of automatic ship identification system data, in addition to signal manipulation to hide their movements. This system allows determining the locations, movement and identity of ships, while interruptions leave gaps in the voyage log and make it difficult to know the location of the ship and the source of its cargo.

The reappearance of the tanker on tracking systems does not mean that its route has become clear, as it may reappear in a different location after a period of interruption, which complicates the reconstruction of its journey and verification of the loading and unloading operations it conducted.

Reuters documented the use of ship-to-ship transfers at sea in Iranian oil trade, instead of direct delivery at ports, which makes it difficult to determine the source of the oil and its original journey, and reduces the chances of linking the new tanker to the origin of the shipment.

The US Treasury also documented the transfer of millions of barrels of Iranian oil between tankers, including operations between ships subject to sanctions and others that were not listed on them, with the aim of distancing the shipments from their direct connection to the Iranian oil sector.

In September 2025, the ministry said that one of the networks used transfers between ships, some of which took place at night and in an unsafe manner, as part of procedures that also included manipulating automatic identification system data to hide the activity.

Evasion attempts do not end with the movement of tankers, but rather extend to the source of the oil itself through commercial arrangements, documents, and intermediary entities. The US Treasury says that networks linked to this trade used front companies and multiple entities to hide the real beneficiaries. It also documented cases of mixing Iranian oil or presenting it as oil from another country, making it difficult to determine the origin of the shipment.

In July 2025, the ministry announced the targeting of a network that it said had made profits from smuggling Iranian oil after hiding it or mixing it with Iraqi oil, in an example of the smuggling operation targeting the identity of the oil itself, and not just the ship transporting it.

Successive American actions demonstrate the size of this system. In December 2025, the US Treasury said that the Office of Foreign Assets Control had imposed sanctions on more than 180 ships since the Trump administration returned to power, and described these tankers as part of the fleet that Iran relies on to transport oil and its derivatives to buyers in Asia.

During 2026, Washington continued to target tankers, companies, and intermediaries linked to Iranian oil trade, in an attempt to disrupt the chain linking Iranian production to transportation, financing, and access to buyers.

China stands out as the most important destination for the bulk of Iranian oil that reaches Asian markets through this network. According to what was reported by Reuters in March 2026, China has become the main customer for Iranian oil, and a large portion of the shipments is transported on old tankers linked to the “Shadow Fleet.”

Last May, the United States imposed sanctions on companies and individuals in Hong Kong and other Asian countries that it said were helping to ship Iranian oil to China, reflecting the network’s expansion outside Tehran and its reliance on multiple parties to complete sales and transportation operations.

Washington faces difficulty in dismantling this system because of its ability to replace ships, companies, and intermediaries, as the inclusion of a tanker on sanctions lists does not necessarily mean that the network operating behind it will stop.

This flexibility prompts the United States to expand sanctions to include, in addition to ships, owners, operators, brokers, service companies, and financial networks associated with Iranian oil trade.

With every port that Washington restricts for Iranian exports, the associated networks seek to find new carriers, different registration data, and alternative routes to maintain the flow of shipments, in a continuous race between tightening restrictions and attempts to bypass them.

The “Cebu 1” incident shows that tracking Iranian oil goes beyond knowing the name of the ship and its destination to tracking a complete chain, starting with the identity and flag of the tanker, passing through its route and the cargo it carries, all the way to the companies and entities behind it.

In this gray space lies the power of the “Shadow Fleet”: a network whose identities and paths constantly change, while its primary mission remains to keep Iranian oil moving on the global market despite the sanctions.