US Destroys Iranian Oil Tankers Using African and Island Flags

U.S. Central Command (CENTCOM) announced that it destroyed five Iranian crude oil tankers after Iran targeted a U.S. Navy warship, with four of the vessels sailing under the flags of African and small island nations rather than Iran. According to CENTCOM and public marine tracking data, the tankers—M/T Kaviz, M/T Charminar, M/T Horizon 1, and M/T Riesco—were struck in the Gulf of Oman, while the M/T Derya was hit near Kharg Island.

The incident highlights ongoing concerns about how Iranian oil shipments use foreign flags to evade international sanctions and monitoring. This practice raises questions about the effectiveness of current oversight and enforcement mechanisms designed to prevent sanctioned countries from moving oil and funding groups such as the Islamic Revolutionary Guard Corps (IRGC).

Tankers’ Flag Registrations

Marine tracking sites indicate that the Riesco was registered under Zimbabwe, a landlocked country with no navy or maritime authority. The Maritime Executive has previously reported that Zimbabwe has no legally registered ships and has been used in false flag operations. The Charminar and Kaviz sailed under the flag of Comoros, a small African archipelago. According to Business Insider Africa, Comoros has become a popular registry for oil tankers linked to Russia and others seeking to avoid sanctions. Since the start of the Russia-Ukraine conflict, the Comorian fleet has expanded by over 270 percent. In response, the United States, United Kingdom, and European Union blacklisted 110 ships flying the Comorian flag last year.

The Horizon 1 was flagged in Palau, a Pacific island nation. The Australian Broadcasting Corporation reported that Palau's shipping registry has rapidly grown, flagging so-called shadow vessels. Palau has since deregistered some vessels and claims to screen ships against sanctions lists to prevent misuse of its flag.

The Derya, according to VesselFinder, was sailing under the Iranian flag at the time of the strike. Built in 2013, its last reported position was near the Indian coast, moving at 2.7 knots.

Sanction Evasion Networks

CENTCOM stated that Iran has used these tankers as part of a multibillion-dollar shadow network that funds the IRGC and its regional proxies. The use of foreign flags, often referred to as "flags of convenience," is part of a broader pattern in which sanctioned countries exploit gaps in maritime regulation. Maritime Crimes, a monitoring website, noted that the flag of convenience system allows vessels to change identity, name, and flag repeatedly—a practice known as "going dark"—which makes international oversight and enforcement more difficult.

The Macdonald-Laurier Institute (MLI) has reported that China also facilitates trade among heavily sanctioned countries, helping Iran, Russia, and North Korea move goods through alternative transportation and payment networks. According to MLI, these shadow fleets often operate on the edges of exclusive economic zones or on the high seas to avoid law enforcement, creating what it described as a "parallel maritime system" for sanction evasion and clandestine activities.

"This flag of convenience system enables vessels to change identity, name, and flag repeatedly, a practice known as ‘going dark,’ which obstructs international monitoring."

— Maritime Crimes, monitoring website

Official Responses and Oversight

CENTCOM’s announcement did not specify any further action against the flag registries involved in the incident. Palau has stated that it screens vessels against sanctions lists and has deregistered some flagged ships in response to concerns about misuse. Officials from Comoros and Zimbabwe have not publicly addressed the use of their flags by Iranian-linked tankers. While the U.S., UK, and EU have taken steps to blacklist vessels using these registries, maritime analysts continue to debate the effectiveness of such measures.

The ongoing use of foreign flags by sanctioned tankers underscores persistent challenges for Western efforts to enforce maritime sanctions and monitor illicit oil shipments. The ability of vessels to change identity and registry, combined with the rapid expansion of certain flag registries, complicates international efforts to track and interdict shipments that may be funding sanctioned entities such as the IRGC.

As the situation develops, the incident serves as a reminder of the evolving tactics used by sanctioned countries to circumvent international controls and the need for continued vigilance and adaptation by regulatory authorities and maritime enforcement agencies.