Iran seizes Chinese-owned oil tanker Ocean Koi amid Strait of Hormuz shipping crisis.

Iranian forces seized the Chinese-linked tanker Ocean Koi during a fast-boat boarding operation near the Strait of Hormuz on May 8, 2026, amid escalating U.S.-Iran military clashes that are now pushing Gulf tanker traffic toward collapse. The interception exposed Tehran’s ability to disrupt global oil flows without formally closing Hormuz, turning commercial shipping, insurance costs and energy markets into active pressure tools in the widening maritime confrontation.

The sanctioned LR1 tanker was already tied to Iran’s shadow oil-export network supplying Chinese refiners through covert ship-to-ship transfers, AIS shutdowns, and offshore ownership structures designed to evade Western sanctions. By targeting a vessel carrying Iranian-origin cargo inside its own sanctions ecosystem, Tehran demonstrated that wartime control over cargo routing, payment channels and tanker access has become as strategically important as missile strikes or naval deployments, reinforcing fears that the Hormuz crisis could trigger a prolonged shock across global crude and LNG markets.

Related topic: US Navy launches first F/A-18 strafing attacks against Iranian tankers in Gulf of Oman

Iran justified the tanker seizure by claiming the Ocean Koi was carrying Iranian oil while allegedly exploiting wartime conditions in the Gulf to disrupt Iranian petroleum exports and harm the country’s national interests. (Picture source: IRIB and Vessel Finder via X/The Maritime)

On May 8, 2026, the Wall Street Journal reported that Iranian naval forces seized the Barbados-flagged LR1 tanker Ocean Koi, also known under the name Jin Li, during a boarding operation in the Gulf of Oman conducted under wartime shipping conditions around the Strait of Hormuz. Iranian footage shared by IRIB showed armed boarding teams using fast attack craft before redirecting the Chinese-owned vessel toward the Iranian coast. Tehran's IRNA agency stated that the tanker carried Iranian-origin petroleum cargo and accused it of disrupting Iranian oil exports during the ongoing U.S-Iran maritime confrontation.

The seizure occurred less than 24 hours after Iranian and U.S forces exchanged missile and drone strikes near Hormuz, while U.S Central Command announced three F/A-18 operations against tankers attempting to reach Iranian ports. For now, roughly 1,600 commercial vessels and nearly 20,000 seafarers remain trapped inside the Gulf due to Iranian and U.S. operations. Before the conflict, roughly 130 merchant ships transited Hormuz daily; by May 2026, traffic periodically fell to near-zero conditions. According to available information, the Ocean Koi, identified by IMO number 9255933, was built in 2004 and belongs to the LR1/Panamax category used for crude oil and refined petroleum transport.

The tanker measures 228.6 meters in length with a 32.2 meter beam and carries roughly 72,768 DWT with a gross tonnage of 41,589 GT. Between 2018 and 2026, the ship cycled through the identities Stena Companion, Genmar Companion, Gener8 Companion, Companion, Rovina, Tania, Daisy 2, Cimarron, Ocean Koi, and Jin Li, while shifting flags between Bermuda, Panama, Comoros, Tanzania, Cameroon, and Barbados registries. These repeated renamings and flag changes matched established sanctions-evasion methods used across Iranian, Venezuelan, and Russian shadow tanker fleets.

The vessel was linked to Ocean Kudos Shipping Company Limited, formally registered in the Marshall Islands but commercially associated with Chinese maritime operations in Shanghai, including an address at Room 1501, 707 Zhangyang Road in Pudong New Area. Washington's OFAC (Office of Foreign Assets Control) sanctioned the tanker and Ocean Kudos Shipping Company Limited on February 25, 2026, under Executive Order 13902, targeting Iran’s petroleum sector and shadow fleet infrastructure. U.S authorities identified the vessel as active inside Iran’s shadow fleet since at least 2020 and linked it to the transportation of millions of barrels of Iranian condensate and high-sulfur fuel oil toward Asian buyers.

At least 16 Iran-linked voyages were identified by TankerTrackers after 2021, with roughly half involving direct Iranian port loadings and the remainder conducted through ship-to-ship transfers in the Gulf of Oman. Routing behavior included prolonged anchorage near Sohar and Fujairah, AIS shutdowns, false destination declarations, manipulated positional transmissions, and loitering patterns associated with covert cargo transfers. The tanker also became associated by Lloyd’s List with suspicious registry documentation and questionable flag certifications after its renaming to Ocean Koi. 

The Ocean Koi seizure, therefore, looks contradictory at first glance because China is Iran’s main oil customer and one of Tehran’s most important economic partners, and because the tanker itself was already operated inside Iran's export schemes. Tehran acknowledged that the vessel carried Iranian-origin cargo at the time of interception, indicating that the dispute was likely internal to Iran’s sanctions economy rather than retaliation against China. The tanker reportedly remained idle near Sohar for prolonged periods after loading Iranian cargoes, possibly due to payment disputes, cargo diversion attempts, resale negotiations, insurance complications, or disputes between intermediaries.

Iran’s petroleum export system is fragmented across National Iranian Oil Company channels, IRGC-linked trading networks, politically connected brokers, and Chinese-linked import structures competing for access to export revenue during sanctions conditions. The seizure, therefore, likely reflected conflict over cargo control, payment settlement, or routing authority inside Iran’s wartime sanctions-evasion network. China became Iran’s dominant oil customer after Western sanctions isolated Tehran from most global markets, importing 1.3-1.6 million barrels per day in 2025-2026, with peaks near 1.8 million bpd, representing 80-90% of Iran’s total crude exports and generating an estimated $35-45 billion annually for Iran.

Iranian crude was typically sold to Chinese independent “teapot” refineries at discounts ranging from $4 to $11 below Brent, with an average 2025 discount near $9/barrel, meaning crude trading at $69 Brent could be sold near $60/barrel to Chinese buyers. The system relied on a massive sanctions-evasion network involving shadow tankers, offshore shell companies, ship-to-ship transfers near Malaysia and Indonesia, false cargo origin declarations, and opaque financing channels using yuan settlements and intermediary firms. For Chinese refiners operating on margins as low as $2-5/barrel, discounted Iranian crude became economically essential because even a $5-10 discount could reduce feedstock costs by 7-14%, significantly boosting refinery profitability despite sanctions risk. 

Chinese buyers currently absorb between 80% and 90% of Iranian crude exports, with import volumes estimated between 1.3 and 1.5 million barrels per day during 2025 and early 2026. Iranian barrels accounted for roughly 13%-14% of Chinese seaborne crude imports during parts of 2025. Cargoes linked to Jin Li likely targeted independent “teapot” refiners concentrated in Shandong Province, particularly around Dongying, Rizhao, and Qingdao. The “teapot” model refers to China’s smaller independent oil refineries, mainly located in Shandong province, which buy discounted sanctioned crude, especially from Iran and Russia, outside the traditional state-controlled refining system.

Because these refiners have limited exposure to Western finance and operate on very thin margins, they are more willing to use shadow shipping networks, ship-to-ship transfers, and opaque payment channels to import cheap oil at $4-11/barrel discounts below Brent. The vessel’s ownership structure matched broader Chinese maritime practices involving offshore incorporation, Shanghai-based operational management, and compartmentalized tanker ownership intended to reduce secondary sanctions exposure. Chinese-linked shipping ecosystems provide the maritime finance, intermediary logistics, and non-dollar settlement channels required to sustain Iranian exports despite restrictions on SWIFT access and Western banking systems.

Ship-to-ship transfers near Malaysia, Indonesia, Fujairah, and the Gulf of Oman increasingly became standard methods for masking Iranian cargo origin before delivery into Chinese refining networks. Iran’s interception methods reflected a mature maritime coercion framework refined through repeated tanker seizures over the last decade. Previous operations involving Stena Impero, Advantage Sweet, Niovi, Talara, and Greek-operated tankers demonstrated a pattern in which Tehran used legal claims linked to smuggling or maritime violations as sovereign cover for politically directed maritime pressure operations.

Standard Iranian interception groups typically combine Boghammar-type fast attack boats, Ashura-class patrol craft, Taregh high-speed boats, and armed RHIBs supported by Bell 412 or Mi-17 helicopters carrying naval commandos, while Shahed drones provide overwatch, surveillance, and targeting, with occasional support from regular Iranian Navy units. Boarding sequences generally begin with aggressive maneuvering and radio warnings before escalating toward forced course alteration, armed intimidation, helicopter overwatch, and rapid seizure of bridge control and communications systems.

Once onboard, Iranian teams prioritize AIS systems, navigation authority, and engine operations before redirecting the vessel toward Bandar Abbas, Qeshm, or another Iranian-controlled anchorage. The seizure occurred during the largest disruption to global tanker markets since the oil crises of the 1970s. Before the conflict escalation, Hormuz handled between 20 and 21 million barrels per day, representing nearly 20% of global oil consumption and close to 30% of seaborne crude trade, in addition to 20%-25% of global LNG flows. Within days of the escalation, tanker traffic through Hormuz reportedly collapsed by more than 90%, while more than 260 tankers and roughly 800 merchant vessels became stranded west of the Strait.

VLCC Middle East-Asia rates surged several-fold above pre-crisis levels of roughly $40,000-$60,000 per day, while war-risk insurance premiums rose from roughly 0.125% of hull value toward 1%-3% during peak crisis conditions. Concretely, this translates into per-voyage insurance costs rising from roughly $125,000 to as much as $1 to 3 million. Several insurers withdrew Gulf coverage entirely or imposed 48-hour cancellation clauses because of deteriorating maritime security conditions. The simultaneous disruption of Hormuz and Red Sea shipping routes forced large-scale rerouting around the Cape of Good Hope, adding between 10 and 20 days to many tanker voyages and sharply reducing effective fleet productivity.

Brent crude surged above $100 per barrel before peaking near $125-$126 per barrel, while more than 10 million barrels per day were temporarily displaced from normal trade flows. LNG markets experienced parallel disruption because nearly all Qatari LNG exports depend on Hormuz transit, contributing to European gas price increases from roughly €30/MWh toward peaks above €60/MWh. Asian importers, including China, India, Japan, and South Korea, absorbed the heaviest refining shock because roughly 84% of Hormuz crude shipments normally flow toward Asia. Iran demonstrated that it did not need to physically close Hormuz permanently in order to destabilize energy markets. By making transit commercially intolerable through interception risk, insurance escalation, shipping delays, and coercive maritime control, Tehran disrupted tanker flows, freight pricing, refinery operations, and global energy confidence simultaneously.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.