Iranian oil tankers: 34 ships tracked under US blockade

Blockade expands from ports to open waters

Maritime tracking groups and media reports are painting a fast-moving picture of Iranian crude shipments under pressure from a US naval blockade that began on April 13. The claims are not uniform. Data firms say multiple tankers continued to move through the Gulf of Oman and beyond, while US Central Command (CENTCOM) has publicly disputed that some named vessels “evaded” the blockade.

The operational geography has also widened. Reports cited shipping and security sources describing interceptions in Asian waters near India, Malaysia, and Sri Lanka, suggesting enforcement is no longer limited to approaches to Iranian ports. Separately, TankerTrackers referenced a “HUGE” vessel moving through Indonesian waters while avoiding US monitoring, with the ship described as carrying more than 1.9 million barrels of crude oil.

What Vortexa says it tracked in the Gulf of Oman

Cargo tracking group Vortexa told ABC News it identified 34 sanctioned or Iranian-linked ships moving in and out of the Gulf of Oman through the US blockade. Vortexa split the observed movements into 15 inbound toward Iran and 19 outbound away from Iran.

From the outbound set, Vortexa said six ships were confirmed to be laden with about 10.7 million barrels of Iranian crude oil. The firm also said the blockade is having some effect, but that flows have continued “in a more constrained and selective environment,” based on observed vessel activity.

TankerTrackers’ count of shipments that passed through

TankerTrackers.com told ABC News it observed nine shipments of Iranian oil pass through the US blockade between April 13 and April 20. It said one of those shipments has been sent back to Iran.

Of those nine shipments, TankerTrackers said eight were tankers belonging to Iran’s National Iranian Tanker Company and one was independently owned. The firm’s separate observation about a “HUGE” vessel referenced more than 1.9 million barrels of crude oil and placed the movement through Indonesian waters.

CENTCOM disputes “evasion” claims for named ships

After Vortexa shared data and media outlets named three ships, CENTCOM publicly refuted that the three had evaded the blockade. CENTCOM said two of those ships, the Hero II and Hedy, had returned to an Iranian port.

CENTCOM also said the Dorena was “under the escort of a U.S. Navy destroyer in the Indian Ocean after previously attempting to violate the blockade.” This response highlights a key fault line in the public narrative: trackers describe movements consistent with continued flows, while CENTCOM describes enforcement actions, turn-backs, and escorts.

Reuters: interceptions reported near India, Malaysia, Sri Lanka

A Reuters report dated April 22 said the US military intercepted at least three Iranian-flagged tankers in Asian waters and is redirecting them away from positions near India, Malaysia, and Sri Lanka, citing shipping and security sources.

Reuters identified the Deep Sea as an Iranian-flagged supertanker that was part-loaded with crude and last seen on public tracking data off Malaysia’s coast about a week earlier. It also described the smaller Iranian-flagged Sevin, with a maximum capacity of 1 million barrels, carrying 65% of its load, and last seen off Malaysia’s coast about a month earlier.

Reuters further reported the Iranian-flagged supertanker Dorena was intercepted while fully loaded with 2 million barrels of crude and last seen off southern India three days earlier. CENTCOM, in a post on X referenced by Reuters, said the Dorena was under escort after attempting to violate the blockade.

The Majestic X question and other reported actions

ABC News noted it was not immediately clear whether the M/T Majestic X, which the US announced it had interdicted in the Indian Ocean for carrying oil from Iran, was also among the ships tracked as having moved through the blockade.

Other reports in the supplied material also describe a widening operational posture, including mention that US forces have “directed 29 vessels to turn around or return to port” since the start of the blockade, and separate references to boardings and seizures of vessels described as Iran-linked or sanctioned.

Why tracking can be contested in real time

One recurring complication in this story is visibility. Vortexa noted that vessels seeking to circumvent US forces typically turn off their transponders, and it said it detected shipments using satellite imagery. That creates space for disagreement about whether a ship “passed through” a blockade line, was turned back, was escorted, or re-entered port after being challenged.

This is also why different datasets can appear to conflict. Trackers can identify likely ship movements and cargo status from imagery and maritime signals, while military statements focus on interdictions, escorts, and compliance outcomes.

What the developments mean for crude market risk

The confirmed figures in the tracking reports point to meaningful volumes still moving even as enforcement actions increase. Vortexa’s confirmation of 10.7 million barrels across six outbound ships, and TankerTrackers’ observation of nine shipments between April 13 and 20, suggest continued flows during the first week of the blockade.

At the same time, CENTCOM’s public rebuttals and Reuters’ reporting on redirections indicate enforcement is active across a wide area, including waters near India and Southeast Asia. For energy markets, the immediate takeaway is not a single “stopped vs not stopped” outcome, but an environment where routes, ship behavior, and cargo delivery attempts are being contested day by day.

Key facts at a glance

What to watch next

The next set of verified signals will likely come from additional CENTCOM updates, fresh satellite-based observations from tracking firms, and clarity on specific vessels mentioned across reports, including whether M/T Majestic X overlaps with trackers’ identified movements. Attention will also remain on ship-to-ship transfer areas referenced in the reports, including routes in Southeast Asia and Indonesian waters.

For investors tracking oil-sensitive sectors, the key near-term variable is the balance between continued observed flows and the pace of interdictions and turn-backs described by the US military. The story is evolving through discrete vessel events, and each confirmed interception, escort, or return-to-port changes the operational picture.