GULF OF OMAN — U.S. military forces boarded an Iranian-flagged oil tanker in the Gulf of Oman that was suspected of trying to violate the American blockade on Iranian shipping. U.S. Central Command said on social media that the M/T Celestial Sea was searched and redirected after being suspected of trying to head to an Iranian port.

At least five commercial vessels have been boarded since the blockade began in mid-April. The Trump administration imposed the blockade several days into a ceasefire to pressure Tehran into opening the Strait of Hormuz and accepting a deal to end the war, which began with U.S. and Israeli airstrikes on February 28.

The U.S. military has enforced the blockade on Iran's ports and on Iranian-linked ships outside the Middle East. U.S. forces boarded an oil tanker in the Bay of Bengal that had previously been sanctioned for smuggling Iranian crude oil, and seized another tanker in the Indian Ocean between Sri Lanka and Indonesia that was associated with smuggling Iranian oil.

U.S. forces also fired on and disabled two Iranian oil tankers in the Strait of Hormuz after exchanging fire with Iranian forces. The U.S. military said those tankers were trying to breach the blockade, and said it thwarted Iranian attacks on three Navy ships and struck Iranian military facilities in response.

The U.S. military said recently that 1,550 vessels from 87 countries are currently stranded in the Persian Gulf. Iran controls maritime traffic through the Strait of Hormuz, and before the blockade allowed some ships perceived as friendly to pass while charging fees.

President Donald Trump said in early May that the U.S. military would begin to guide stranded ships from the Strait of Hormuz, then announced the next day that the effort to protect ships was paused to see if an agreement could be reached.

Trump said on Monday that he had called off renewed military strikes on Iran to make progress in negotiations to end the war. He said he had planned a major attack for Tuesday but postponed it after America's allies in the Gulf asked him to wait two to three days. Trump has repeatedly set deadlines for Tehran and then backed off.