This is a developing story. Check back for updates. 

A cargo ship has been seized by Iranian naval forces and taken to the Persian Gulf port of Bandar Abbas, on the Strait of Hormuz, a tweet Tuesday from the Saudi Arabian-owned Al Arabiya news website reported. According to al Arabiya 34 sailors on board the vessel are American, although U.S. officials later said that the ship, bearing the flag of the Marshall Islands, has no American sailors on board.

Iran's FARS news agency said the vessel had been detained "for trespassing in Iran's territorial waters."

While it's not yet clear where the ship was intercepted, a live feed on ship tracking site shows one ship with the Marshall Islands' flag, the Maersk Tigris, in the Iranian port of Bandar Abbas. The ship was on its way from Jeddah, Saudi Arabia, to the port of Jebel Ali in Dubai, United Arab Emirates, the website reported. The Pentagon has confirmed that the ship seized by Iran is the Maersk Tigris. 

Reuters reported that the ship had been chartered by Maersk Line, the biggest container shipper in the world, and was operated by  Singapore-based Rickmers Ship Management, part of Rickmers Group, which is based in Germany.

"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 Pentagon spokesman Col. Steve 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 and the USS Farragut, a destroyer, was deployed to investigate. It's not yet clear what the destroyer may do when it reaches the area. 

The Tigris' tracking data shows it navigating in international waters through the Strait of Hormuz early Tuesday morning before suddenly changing course toward Iranian territorial waters and the port of Bandar Abbas. 

Maersk Tigris The Maersk Tigris is believed to be the ship that Iranian authorities fired upon and seized on Tuesday. Photo: Screenshot

While the ship does not belong to a company from the United States, the fact that it is registered in the Marshall Islands is politically important to the U.S. A little-known treaty between the two states makes the U.S. responsible for the Pacific island nation's defenses.

"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," states the Compact of Free Association signed in 2003 between the two. 

Senior U.S. military officials, speaking Tuesday to NBC, said there have not been any confrontations between Iranian and U.S. military ships operating in the region. U.S officials said the nuclear-powered aircraft carrier USS Theodore Roosevelt was off the coast of Oman as of April 22, and the USS Iwo Jima, an amphibious assault ship, off the Horn of Africa in the Red Sea. Around ten American naval ships in all are reported to be in the region. 

The report of the cargo ship being seized comes just days after an Iranian convoy of ships, reportedly on its way to deliver weapons to Houthi rebels in Yemen, turned back before meeting U.S. Navy ships operating in the Gulf of Aden.