Incident:
On 20 May 2026, U.S. Marines boarded the Iranian-flagged oil tanker M/T Celestial Sea after suspecting it of attempting to breach the U.S. blockade on Iran. Following a search, American forces released the vessel and instructed its crew to alter course. U.S. military officials stated that a total of 91 vessels have now been redirected to ensure compliance with the blockade.
Vessel seizure by state/non-state actor: If boarded by military or paramilitary personnel, safety of vessel and crew is paramount. Maintain a de-escalatory posture and obey all commands, consistent with ship’s safety and navigational constraints. Maintain communications for as long as possible with maritime authorities (e.g. UKMTO, MSCIO). Allied Naval vessels may be monitoring the situation but intervention cannot be relied upon.
