Iranian forces boarded a Marshall Islands-flagged cargo ship April 28 in the Strait of Hormuz, the U.S. said, refuting an erroneous report that the seized vessel was American.

U.S. Naval Forces Central Command in Bahrain answered a distress call after an Iranian vessel fired shots across the bridge of the ship and a destroyer was dispatched to the strait. The ship, the MV Maersk Tigris, is owned by Danish company Maersk.

Despite the ruckus, crude oil and petroleum products both finished the day lower as little in terms of headlines justified any rally, said Andrew Fletcher, senior vice president, KeyBank National Association.

“We did have some excitement briefly this morning where the market rallied almost $1 per barrel on the prompt contract as news hit the wires of the Iranians seizing a U.S. ship. On further investigation the ship was found to be Danish and none of the crew were American,” Fletcher said.

The Maersk Tigris was fired at by patrol boats and boarded at about 9 a.m. GMT on Tuesday, after the captain refused an order to move deeper into Iranian waters, Army Colonel Steve Warren told reporters at the Pentagon.

The ship’s master then complied with the Iranian demand and proceeded into Iranian waters near Larak Island, the Pentagon said. Larak Island is off the coast of Iran in the Persian Gulf.

In addition to a destroyer, U.S. aircraft are monitoring the ship. The Republic of the Marshall Islands is a sovereign nation for which the U.S. has full authority and responsibility for security and defense under the terms of an amended compact entered into in 2004.

The ship was on an “internationally recognized maritime route” when it was intercepted by the Iran’s Islamic Revolutionary Guard Corps naval force, State Department spokesman Jeff Rathke told reporters in Washington. Cor Radings, an external spokesman for Rickmers Ship Management, the vessel’s manager, said it was in international waters and it wasn’t clear why it had been halted.

Iran’s Fars news agency said the vessel was seized by the navy, which was acting on a court order for its confiscation due to a financial dispute between the Iranian ports authority and the ship’s owners. The 34-member crew includes European nationals, Fars said.

The incident followed one that happened April 24 when four Iranian naval vessels surrounded the U.S.-flagged Maersk Kensington in the Strait of Hormuz, CNN said in a news report citing the U.S. Navy as its source. The news agency reported that a senior U.S. military official said "the Iranians encircled the Kensington and followed the ship on its course for a period of time before withdrawing and breaking away." The situation prompted the U.S. Navy Fifth Fleet to issue a notice to mariners about the incident.

Oil Surge

Saudi-owned Al-Arabiya television earlier reported that the Iranians had seized an American ship April 28, prompting a surge in oil prices. Brent crude rose as much as 1%, before paring most of the gains as it emerged that the report was inaccurate. It traded at $64.87 a barrel at 1:45 p.m. in New York, up 0.1% from the previous day’s close.

The waterways of the Persian Gulf, a region that holds about half the world’s oil, remain a potential flash point even as ties between the U.S. and Iran improve.

The two countries have cited progress in recent months in talks on a nuclear accord. They’re still opposed on many Middle Eastern issues, including the escalating war in Yemen where the U.S. supports the Saudi-backed government and Iran has ties with Shiite rebels.

Hart Energy editors contributed to this report.