U.S. Marines Board Iranian Tanker in Gulf of Oman

U.S. Marines boarded and redirected an Iranian-flagged oil tanker in the Gulf of Oman on Tuesday as Washington continued tightening enforcement of its maritime blockade targeting vessels trading with Iran.

In a statement posted to X, the U.S. military’s Central Command said Marines from the 31st Marine Expeditionary Unit boarded the tanker M/T Celestial Sea after the vessel was suspected of attempting to violate the blockade by transiting toward an Iranian port.

“Earlier today in the Gulf of Oman, U.S. Marines from the 31st Marine Expeditionary Unit boarded M/T Celestial Sea, an Iranian-flagged commercial oil tanker suspected of attempting to violate the U.S. blockade by transiting toward an Iranian port,” CENTCOM said. “American forces released the vessel after searching and directing the ship’s crew to alter course.”

Video of the boarding appears to show the same vessel featured in an earlier CENTCOM post published Tuesday showing U.S. forces blocking an unidentified merchant ship as part of the blockade against Iran.

CENTCOM forces continue total enforcement of the U.S. blockade against Iran, stopping the flow of commerce into and out of Iranian ports. 89 commercial vessels have been redirected to ensure compliance. pic.twitter.com/0MWwUvkDgS

— U.S. Central Command (@CENTCOM) May 19, 2026

CENTCOM said U.S. forces have now redirected 91 commercial ships since enforcement operations began. As of May 20, American forces have also disabled four vessels accused of attempting to violate the blockade.

The Trump administration’s blockade, announced in April, targets vessels entering or departing Iranian ports while technically allowing commercial traffic transiting the Strait of Hormuz to non-Iranian destinations.

The maritime enforcement campaign intensified sharply earlier this month when U.S. Navy aircraft disabled multiple Iranian-flagged tankers operating near the Gulf of Oman.

On May 8, CENTCOM confirmed that U.S. Navy F/A-18 Super Hornets launched from the aircraft carrier USS George H.W. Bush disabled the tankers M/T Sea Star III and M/T Sevda by firing precision munitions into the vessels’ smokestacks.

That operation followed a May 6 incident involving the tanker M/T Hasna, where an F/A-18 launched from USS Abraham Lincoln fired 20mm cannon rounds into the vessel’s rudder after it allegedly ignored repeated warnings from U.S. forces.

CENTCOM has repeatedly said the operations are intended to enforce the blockade and prevent vessels from entering Iranian ports.

The conflict continues to deepen disruption across global shipping markets and regional energy trade. Commercial traffic through the Strait of Hormuz remains severely reduced compared to pre-conflict levels as shipowners weigh missile threats, sea mines, drone attacks and soaring war-risk insurance premiums.

Industry groups including BIMCO and the International Chamber of Shipping have warned that commercial operators remain caught between rapidly evolving military operations, unclear transit guarantees and mounting security threats inside the Gulf.

BIMCO Chief Safety & Security Officer Jakob Larsen previously warned that abrupt operational changes — including the Trump administration’s suspension of “Project Freedom,” the short-lived U.S. escort initiative for stranded vessels — have made voyage risk assessments increasingly difficult for commercial shipowners.

Humanitarian concerns are also mounting for thousands of seafarers still trapped aboard vessels inside the Gulf region as operators continue delaying or avoiding Hormuz transits altogether.

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