DUBAI/WASHINGTON Iranian forces boarded a Marshall Islands-flagged cargo ship in the Gulf on Tuesday after patrol boats fired warning shots across its bow and ordered it deeper into Iranian waters, the Pentagon said. 
 
 U.S. planes and a destroyer were monitoring the situation after the vessel, the MV Maersk Tigris, made a distress call in the Strait of Hormuz, one of the world's most important oil shipping channels. 
 
 Iran's Tasnim news agency quoted an unidentified source who sought to play down the incident, saying it was a civil matter with no military or political dimension. But the Pentagon described it as an apparent provocation. 
 
 The incident came as the United States and five other global powers aim to secure a final nuclear deal with Iran by the end of June. 
 
 Under the accord Tehran, which denies seeking to build nuclear weapons, would win sanctions relief in return for slashing the number of its uranium enrichment centrifuges and accepting intrusive international inspections. 
 
 Saudi-owned Al Arabiya television earlier said an Iranian force fired on and seized a U.S. cargo ship with 34 U.S. sailors on board, and directed it to the Iranian port of Bandar Abbas. But the Pentagon spokesman said there were no U.S. citizens on board the ship. 
 
 The company managing the vessel told a Danish news channel there were 24 crew members, mostly from eastern Europe and Asia. 
 
 Reuters tracking data showed the Maersk Tigris, a 65,000-tonne container ship, off the Iranian coast between the islands of Qeshm and Hormuz. It had been listed as sailing from the Saudi port of Jeddah, bound for the United Arab Emirates port of Jebel Ali. 
 
 COURT ORDER 
 
 Iran's Fars news agency said the ship was seized at the request of Iran's ports authority under a court order. 
 
 But a spokesman for the Singapore-based company that manages the vessel, which usually includes hiring the crew, Rickmers Shipmanagement, said he did not know why Iran had taken action. 
 
 Spokesman Cor Radings confirmed to Danish TV2 news channel that Iranian forces fired warning shots at the container ship and boarded it, and said the company was concerned for the crew. 
 
 The vessel had been following a normal commercial route between Saudi Arabia and the United Arab Emirates, he said. 
 
 A U.S. government official said the ship was intercepted by the Naval force of Iran’s Islamic Revolutionary Guard Corps (IRGC) at 0905 GMT. 
 
 Another U.S. official said that when the warning shots were fired, the Maersk Tigris issued a distress call which was received by U.S. forces operating in the region. 
 
 The closest U.S. warship was more than 60 miles away, he said, and the U.S. military instructed destroyer USS Farragut to head towards the cargo ship, which was passing through the Strait of Hormuz at the time. 
 
 Some 17 million barrels per day (bpd), or about 30 percent of all seaborne-traded oil, passed through the channel in 2013, according to the U.S. Energy Information Administration (EIA). 
 
 Iran has in the past sometimes threatened to block the strait to advance its opposition to sanctions imposed over its nuclear program. 
 
 The channel is a narrow strip of water separating Oman and Iran. It connects the biggest Gulf oil producers, such as Saudi Arabia, with the Gulf of Oman and the Arabian Sea. 
 
 At its narrowest point, the strait is 33 km (21 miles) across and consists of 2-mile wide navigable channels for inbound and outbound shipping and a 2-mile-wide buffer zone. 
 
 (Additional reporting by Phil Stewart, Leslie Wroughton and Mark Hosenball in Washington, Sabina Zawadzki in Copenhagen, Jonathan Saul in London, Yara Bayoumy in Cairo and Sam Wilkin in Dubai; Writing by Dominic Evans; Editing by Janet Lawrence) ||||| Washington (CNN) A U.S.-flagged ship was recently intercepted by an Iran Revolutionary Guard naval patrol, the U.S. Navy revealed to CNN Tuesday. 
 
 The incident occurred on Friday when four Iranian naval vessels surrounded the U.S.-flagged Maersk Kensington in the Strait of Hormuz. 
 
 The episode came ahead of an encounter Tuesday in which Iran Revolutionary Guard patrol boats fired shots at a commercial cargo ship and then intercepted the vessel, the Marshall Islands-flagged M/V Maersk Tigris, which was also crossing the Strait of Hormuz. 
 
 A senior U.S. military official told CNN that "the Iranians encircled the Kensington and followed the ship on its course for a period of time before withdrawing and breaking away." After that, the U.S. Navy Fifth Fleet issued a notice to mariners about the incident. 
 
 The crew of the Maersk Tigris container ship is "safe and under the circumstances in good spirits," Danish shipping company Maersk said Wednesday in an emailed statement to CNN. The Pentagon estimates that about 30 individuals are on board. 
 
 On Tuesday night, the cargo ship was being escorted toward Bandar Abbas on the coast of Iran by Iranian patrol boats, but it has not reached the shore. It's currently about 9 miles due south of the port. 
 
 Maersk said they are still unable to "establish or confirm the reason" for the seizure, and remain in close dialogue with the Danish Foreign Ministry. 
 
 Referring to Tuesday's incident, Pentagon spokesman Col. Steve Warren said it was "inappropriate" for the Iranians to fire the warning shots. 
 
 The U.S. Navy has dispatched one maritime patrol and reconnaissance aircraft to observe and monitor the situation, Warren told reporters. 
 
 Despite reports in some media, there are no Americans on board, according to a U.S. official. 
 
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 At this point, no U.S. military action is expected on the ship that was seized Tuesday aside from monitoring the situation. The U.S. believes that Iranians will "send the ship on its way," the senior official said. 
 
 State Department spokesman Jeff Rathke noted Tuesday afternoon that he U.S. has a security compact with the Marshall Islands on defense issues. 
 
 But he added that there hasn't been a specific request for assistance from the Marshall Islands and said it was premature to say whether this could require the use of force. 
 
 He did state, however, that "it's a key concern of the United States to ensure that sea lanes in the region remain open and safe." 
 
 In Tuesday's incident, the Marshall Islands-flagged vessel was transiting the Strait into the Persian Gulf on an internationally recognized maritime route when 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 that 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 away. 
 
 "We have been in communication with U.S. shipping industry representatives with regards to how their vessels should respond to threatening encounters with foreign naval forces and how to contact us, " the U.S. official said, declining to provide the specific advice being given. In the incident Friday, no shots were fired. 
 
 The senior official pointed out that that historically, Iran Revolutionary Guard naval forces have been more likely to be engaged in hostile contact with the shipping and military vessels in the region than the regular Iranian navy. Contact with regular Iranian naval forces is frequent and "professional," the official said. 
 
 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, Iran's semi-official news agency 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. 
 
 Maersk LInes issued a statement Tuesday that the company's "paramount concern is the safety and well-being of the crew."
– Iran is rattling sabres in the Strait of Hormuz today: Iranian warships have boarded a Marshall Islands-flagged cargo ship—after firing warning shots, reports Reuters—and ordered it to "divert further into Iranian waters," adds CNN, quoting a US official. The M/V Maersk Tigris was reportedly on a recognized maritime route when the Iranians approached, and the shipmaster "initially declined" the order; the warning shots proved persuasive and the Tigris issued a distress call. The USS Farragut is responding along with aircraft, reports CNN; the closest American warship was 60 miles away. There are no American citizens aboard the Tigris.