US Marines Board Iranian-Flagged Oil Tanker Amid Heightened Blockade Enforcement

Marines from the 31st MEU boarded M/T Celestial Sea in the Gulf of Oman on 20 May 2026, searched it, ordered a course change, and released the vessel.

US military boards Iranian-flagged oil tanker in Gulf of Oman, releases after search

Mid-April 2026 the United States announced a maritime blockade to pressure Tehran to reopen the Strait of Hormuz, targeting vessels entering or leaving Iranian ports. Prior actions include disabling the tankers Sea Star III, Sevda, Hasna and boarding commercial ships.

The Hill

President Donald Trump, U.S. Central Command (CENTCOM), the 31st Marine Expeditionary Unit, the Iranian Revolutionary Guard Corps (IRGC) and the U.S. Senate are the principal actors. Trump halted a planned “very major attack” after Gulf allies urged a pause, later saying the delay could save lives. CENTCOM directed the boarding as a compliance check and affirmed that the blockade remains fully enforced. The IRGC warned that any renewed U.S. strikes would broaden the conflict beyond the Middle East. The Senate passed a 50-47 bill to compel a presidential withdrawal from the Iran war.

Bloomberg

CENTCOM reports 91 ships redirected; GCaptain cites 89, a minor discrepancy. About 1,550 vessels from 87 countries are stranded in the Persian Gulf, though some sources say “over 1,500.” The Celestial Sea boarding is at least the fifth commercial vessel intercepted since the blockade began.

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

Republican senators introduced legislation to force a presidential pullback amid rising gasoline prices. Shipping groups BIMCO and the International Chamber of Shipping warn that abrupt policy shifts—such as suspending “Project Freedom”—complicate risk assessments and threaten traffic through the Strait of Hormuz.

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

• “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,” — U.S. Central Command (CENTCOM)

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

• “American forces released the vessel after searching and directing the ship’s crew to alter course.” — U.S. Central Command (CENTCOM)

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

• “U.S. forces continue to fully enforce the blockade and have now redirected 91 commercial ships to ensure compliance,” — U.S. Central Command (CENTCOM)

US military boards Iranian-flagged oil tanker in Gulf of Oman, releases after search

• “Let's see what happens.” — President Donald Trump

TND - The National Desk

The US military plans to resume guiding stranded ships while maintaining blockade pressure as talks proceed. Senate debate over the war-ending bill will intensify before the November midterms, and IRGC’s warning signals a risk of escalation if further strikes are authorized.

PBS News Hour