A Singapore-flagged commercial cargo ship was attacked Thursday in the Strait of Hormuz, forcing the U.N. International Maritime Organization to pause its efforts to escort vessels through the vital global energy chokepoint.

Two senior U.S. officials told The Wall Street Journal that Iran's Islamic Revolutionary Guard Corps carried out the attack. The vessel, Ever Lovely, sustained damage to its bridge, and there were no casualties.

It is unclear whether the attack will affect the memorandum of understanding signed by the U.S. and Iran last week. The MOU established a 60-day framework while the sides work toward a permanent deal. The agreement requires Iran to make its best efforts to ensure the safe passage of commercial vessels through the strait in return for lifting the U.S. naval blockade of its ports.

As part of the pact, the U.S. waived sanctions on Iranian oil sales this week and allowed Tehran to sell its crude in dollars for the first time in decades.

Asked whether the reported attack could affect the MOU with Iran, a U.S. official told Newsmax: "We are aware of these reports and looking into them. President [Donald] Trump has been clear that Iran cannot subvert the free flow of traffic in the Strait."

IMO Secretary-General Arsenio Dominguez said in a statement Thursday that he was "informed of an attack today in the Gulf of Oman on a vessel which passed through the Strait of Hormuz." He said the vessel "did not transit under IMO's evacuation framework."

"I have always reiterated that the safety of the seafarers remains paramount," he said. "Therefore, to ensure a coordinated approach and navigational safety, the evacuation plan will be paused until further clarity is obtained."

The IMO on Tuesday announced it was coordinating an evacuation route "for over 11,000 seafarers still stranded in the region" since the U.S.-Israeli conflict with Iran began Feb. 28.

"This large-scale operation will be carried out in close cooperation with Iran, Oman, all other coastal States in the region, the United States and the maritime industry," the IMO said in a news release. "We have secured the necessary safety guarantees and have thoroughly verified the conditions for safe navigation to support these operations.

"We remain fully committed to ensuring the safety of seafarers and the continuity of global trade."

The IRGC said Thursday on its official Telegram channel that three tankers using the southern route sanctioned by the IMO were ordered to turn back, according to the Journal. Maritime intelligence firm Windward said in a report Thursday that five vessels made U-turns.

The IRGC had warned any attempt to cross the strait along a route designated by the IMO would be "unacceptable and completely dangerous" and all vessels should coordinate with Iran.

Before the attack, Ever Lovely loaded cargo at Umm Qasr, Iraq, and set out for Singapore, the Journal reported, citing ship tracker Marine Traffic. The ship's owner, Evergreen Marine Asia Pte Ltd in Singapore, couldn't be reached for comment.

Ever Lovely had been stuck in the Persian Gulf for more than 100 days, the Journal reported, citing financial data provider LSEG. It sailed toward the mouth of the strait Thursday morning local time, joining three other ships that also were attempting to cross the strait at about the same time.

All four ships followed the route identified by the IMO, hugging the Omani coast, the Journal reported, citing ship-tracking data and crew members aboard a nearby vessel. Ever Lovely was sailing the fastest and leading the group. There was no radio warning from the Iranian navy directing the ships to turn back, according to seafarers in the flotilla.