Iran Revolutionary Guard patrol boats fired shots at a commercial cargo ship and then intercepted the vessel, the M/V Maersk Tigris, which was crossing the Strait of Hormuz Tuesday morning, according to a senior U.S. military official.
Despite reports in some media, there are no Americans on board, the official said.
Pentagon spokesman Col. Steve Warren said it was "inappropriate" for the Iranians to fire the warning shot. The U.S. Navy has dispatched one maritime patrol and reconnaissance aircraft to observe and monitor the situation, Warren told reporters.
The ship, a Marshall Islands-flagged vessel, was transiting the Strait into the Persian Gulf on an internationally recognized maritime route when the the Iranian military contacted the vessel and directed the ship master to "divert further into Iranian waters," according to Warren.
"The master was contacted and directed to proceed further into Iranian territorial waters. He declined and one of the IRGCN craft fired shots across the bridge of the Maersk Tigris," said Warren, referring to the Iranian Revolutionary Guard Corps Navy. "The master complied with the Iranian demand and proceeded into Iranian waters in the vicinity of Larak Island."
After the shots were fired, the Tigris issued a distress call which was picked up by U.S. forces in the area and the USS Farragut was ordered to head towards the incident. The closest U.S. warship was 60 miles from the incident. The Pentagon thinks about 30 individuals are on board.
The U.S. Navy has also sent aircraft to monitor its status.
According to the shipping company, which is in contact with the U.S. military, the Iranian military has boarded the ship.
Even though the Strait of Hormuz is in Iranian territorial waters, "innocent passage" is applied -- ships are authorized to pass through the body of water assuming they abide by all the rules of the sea -- because it is an internationally recognized shipping lane.
Warren said it was "to be determined" what the USS Farragut will do when it reached the vicinity of the incident.
The M/V Maersk Tigris was seized at the request of Iran's Ports and Maritime Organization (IPMO), Iran's semi-official FARS is reporting, citing informed sources. The Marshall Islands-flagged vessel was seized after a relevant court order was issued according to the source, indicating that the IPMO had monetary differences with the ship owner.
It's significant that the vessel is from the Marshall Islands because of the Compact of Free Association between the U.S. and the Islands makes the U.S. responsible for its defense.
"The government of the United States has full authority and responsibility for security and defense matters in or relating to the Republic of the Marshall Islands," the treaty states.