In the year leading up to its dramatic seizure by U.S. forces in the Indian Ocean, the oil tanker known as MT Tiffany made several trips between Iran and waters off the coast of Malaysia, about 90 miles from Singapore’s glittering skyscrapers.
During these voyages, they often wandered into small areas before dropping anchor and switching off the required Automatic Identification System (AIS), according to MarineTraffic data reviewed by CNN.
After some time, sometimes hours, sometimes days, the ship reappeared on the AIS.
Tuesday’s seizure of the MT Tiffany and the 1.9 million barrels of Iranian oil it was carrying, according to U.S. officials, has pushed the war with Iran into Indo-Pacific waters, thousands of miles from the Persian Gulf.
It also spotlights this area off the coast of Malaysia, which is about half the size of Rhode Island. According to experts and CNN analysis, the waters serve as Iran’s offshore gas station, used by its shadow fleet to trade and store oil, pumping the regime with much-needed cash as the war rages on.
Although not officially defined, this area is commonly known as the Eastern Outer Port Limit (EOPL) anchorage. It is located near the eastern entrance of the Singapore Strait, one of the world’s busiest shipping lanes, and is within the country’s exclusive economic zone (EEZ) approximately 63 miles off the coast of Peninsular Malaysia. It is best seen in satellite images, where hundreds of ships can sometimes be seen roaming the area.
MT Tiffani can also be identified by IMO number 9273337. This number, assigned by the International Maritime Organization, cannot be changed, regardless of ownership or flag.
According to satellite images seen by CNN, it was seen once in the area in August last year, unloading unspecified cargo onto another ship called the Macho Queen (IMO: 9238868). After the transfer, the Macho Queen briefly turned on its AIS and began sailing northeast toward China, but then turned off its tracking devices again in response to U.S. sanctions for smuggling Iranian oil into China.
A second oil tanker, the MT Majestic
Farzin Nadimi, a senior researcher specializing in Iran at the Washington Institute, said EOPL is a hotspot for the shadow fleet because of its convenient location and the permissive attitude of nearby authorities.
“This is a very convenient place to hide and be active,” Nadimi said. “Malaysian authorities are basically looking elsewhere.”
At least 679 ship-to-ship transfers took place in EOPL in 2025, up from 471 in 2024 and 280 in 2023, according to satellite data compiled by the nonprofit Alliance Against Nuclear Iran (UANI). These numbers underestimate the real situation, as satellites do not pass by every day and ships cannot be detected in bad weather.
CNN has reached out to the Malaysian government for comment.
In July last year, Malaysia pledged to step up crackdowns on illegal ship-to-ship transfers in its waters, with Foreign Minister Mohammad Hasan admitting the issue was “a thorny issue for us,” state media Bernama reported.
According to Bernama news agency, Mohamad said that under the new regulations, vessels that are caught carrying out illegal transfers will be seized.
“We no longer want to be accused of being a country that promotes such activities.”
Iran is one of the world’s leading oil producers, exporting an average of 1.69 million barrels per day in 2025, according to trade data and analysis firm Kpler. According to the US government, about 90% of oil goes to China. China has not imposed sanctions on Iranian crude oil and says it opposes sanctions on Iranian crude oil.
Because of widespread sanctions, Iran relies on an aging tanker fleet with opaque records and shaky insurance to transport crude oil around the world.
Most of that shadow fleet is made up of very large crude carriers (VLCCs), huge tankers like the MT Tiffany that can hold up to 2 million barrels of oil, according to energy data firm Vortexa.
Much of Iran’s sanctioned oil is sold at a discount, about $10 less than the world benchmark Brent crude, which has soared to more than $100 a barrel since the war began, and each ship-to-ship transfer means tens of millions of dollars in revenue for the Iranian regime.
EOPL’s activities have continued since the United States and Israel launched a war against Iran at the end of February, restricting the flow of oil from the Middle East. UANI tracked at least 250 ship-to-ship transfers at EOPL berths between January and April 21 this year.
Iran’s use of the region allowed it to maintain steady exports throughout the war, providing funding for the Iranian regime even as the world grappled with severe oil shortages.
UANI Senior Advisor Charlie Brown highlighted Iran’s shadow fleet, saying, “This is essential to Iran’s business model.”
Ship-to-ship transfers are a routine part of legitimate long-distance shipping and are used to increase efficiency and avoid ports.
Large oil tankers have too deep a draft to enter most ports, so they frequently unload their cargo onto smaller ships. However, these maneuvers involve safety and environmental risks and are highly regulated, must occur in approved areas, and require thorough documentation and notification to coastal authorities.
Shadow fleets use ship-to-ship transfers to obscure the origin of the oil they are shipping, even when it is not logistically necessary. They often block or disguise AIS and run late at night, making it difficult for authorities to detect.
Broadly speaking, Iran’s shadow oil trade follows a similar pattern, involving two ships transporting Iranian crude oil to China.
The first set of ships will primarily receive crude oil from Kharg Island, Iran’s main export facility, and will cross the Indian Ocean through the Straits of Malacca and Singapore, before anchoring off the coast of Malaysia.
The second set of vessels is known for receiving crude oil via ship-to-ship transfers and transporting it to “teapot” refineries, primarily in Shandong province, to purchase sanctioned crude oil.
Ying Kong La, an oil market analyst at Kpler, said China has not officially declared that it imports Iranian crude and often obscures the origin of the oil from Malaysia.
CNN has contacted China’s Ministry of Foreign Affairs for comment. Earlier this month, when asked about the U.S. assessment that China would not stop purchasing Iranian oil, a ministry spokesperson said Beijing “opposes unilateral sanctions that have no basis in international law.”
Brown, a senior adviser at UANI, said that while most of the ships carrying oil from Iran to Asia are on the US blacklist, the majority of ships that pick up the crude and transport it to China are not yet sanctioned.
Shadow fleets also falsify documents, fly false flags or “flags of convenience,” frequently change registrations, and misrepresent cargo to deceive authorities.
“They create new cargo and new stories for new ships,” said Nadimi of the Washington Institute, adding that crews may even paint new names and flags on ships. “This is a cargo cleaning business.”
Malicious activity at EOPL has long been an open secret in the shipping industry. Brown estimates that about 95% of the ships carrying cargo in the region are smuggling Iranian or Russian oil to China.
Nadimi said EOPL also serves as a type of oil storage site for Iran, helping to ease disruption to shipping traffic in the Persian Gulf.
“They (Iran) want to transport as much cargo, as much crude oil as possible, as close to their customers as there is a risk of fighting breaking out in the Strait of Hormuz in the Gulf region.”
According to Kupler, Iran stored a record 191 million barrels at sea in February, accounting for much of East Asia.
According to UANI, this floating strategic stockpile has allowed Iran to maintain high exports, shipping an average of 1.1 million barrels per day to China despite US and Israeli attacks on the country throughout March. Although exports are down from typical volumes, high oil prices are helping offset the financial hit to the regime.
The MT Tiffany may have been unloading cargo at EOPL when the US military boarded it.
According to Marine Traffic data, the ship remained in the Strait of Hormuz and around the Persian Gulf during the month of its seizure. Although the tanker had its AIS disabled, CNN was able to locate the tanker anchored on Iran’s Kharg Island from satellite images taken on April 6.
The tanker reappeared on AIS on 10 April and was spotted sailing southeast in the Gulf of Oman. Data from MarineTraffic showed it was headed for Singapore.
On April 21, the tanker suddenly changed course after passing Sri Lanka. First we made a sharp 90-degree turn to the south, then another 90-degree turn to the east. Immediately after the ship made this change of course, the United States announced its seizure.
A video posted by the Pentagon shows U.S. troops boarding the MT Tiffany as helicopters circle overhead.
Mount Tiffani has been roaming the area ever since.
