The Iranian navy boarded and briefly seized a Liberian-flagged oil tanker near the strategic Strait of Hormuz, a US military official said Thursday.
The US military's Central Command published a black-and-white video showing what appeared to be special forces fast-roping down from a helicopter onto the MV Wila.
The Iranian navy held the vessel for some five hours before releasing it Wednesday, said a US military official who spoke to The Associated Press (AP) on condition of anonymity to discuss details not yet made public.
The Wila made no distress calls before, during and after the seizure, the official said.
The Iranian helicopter involved appeared to be a Sikorsky SH-3 Sea King, which only Iran's navy operates. Two other Iranian naval vessels took part in the seizure, Central Command said.
The US military officials did not offer any reason for Iran seizing the vessel. Iranian state media and officials did not immediately acknowledge the seizure or offer a reason for it.
The Wila's registered owner is a Liberian firm called Bandit Shipping Co., managed by Greek firm IMS SA, according to United Nations records.
Private maritime intelligence firm Dryad Global said it suspected two other ships had been harassed by Iran's paramilitary Revolutionary Guard in the Arabian Gulf over the last week as well, based on the ships' behavior.
According to AP, as tensions between Iran and the US heated up last year over Washington's unilateral withdraw from its 2015 nuclear deal, tankers plying the waters of the Mideast became targets.
Suspected limpet mine attacks the US blamed on Iran targeted several tankers. Iran denied being involved, though it did seize several tankers.