"U.S. Marines have custody of the vessel," Trump said.
President Donald Trump announced "major combat operations" against Iran on Feb. 28, with massive joint U.S.-Israeli strikes targeting military and government sites.
After initial U.S.-Iran talks in Pakistan failed to reach a peace deal, Trump announced Sunday, April 19, that U.S. negotiators would head back to Islamabad Monday for a new round.
White House press secretary Karoline Leavitt said Vice President JD Vance would accompany special envoy Steve Witkoff and Jared Kushner, the president's son-in-law, to Islamabad for the talks.
Iran's continuing blockage of the Strait of Hormuz and their alleged refusal to abandon their nuclear program remain key sticking points in negotiations, according to Trump.
Nine vessels have been turned around at the Strait of Hormuz during the first 48 hours of the U.S. blockade, complying with U.S. orders, according to U.S. Central Command.
"During the first 48 hours of the U.S. blockade on ships entering and exiting Iranian ports, no vessels have made it past U.S. forces," according to CENTCOM.
Pakistan’s Chief of Army Staff General Asim Munir arrived in Tehran on Wednesday leading a Pakistani delegation, the official Islamic Republic News Agency (IRNA) reported.
He was welcomed by Iranian Foreign Minister Abbas Araqchi.
Earlier on Wednesday, Iranian state TV IRIB reported that a high-ranking political and security delegation from Pakistan would arrive in Tehran carrying a new message from Washington. The report added that the delegation is expected to discuss upcoming talks with Iranian officials.
Overnight, ship tracking firms and analysts observed sanctioned crude oil tanker Alicia cross the Strait of Hormuz inbound, from the Gulf of Oman into the Persian Gulf.
Michelle Wiese Bockmann, analyst with shipping analytics company Windward, said the ship is falsely flagged, not currently carrying cargo.
Alicia's crossing was made westward into the Persian Gulf, and the tanker was already in the Gulf of Oman before the blockade came into effect earlier this week. The ship is also listing a destination of "for order" rather than a specific port destination.
Another ship, the Iranian-flagged RHN, appears to be making the same journey across the Strait right now, according to Marine Traffic. It was also already in the Gulf of Oman when the blockade began.
-ABC News' Victoria Beaulé
China has "agreed not to send weapons to Iran," is "very happy" that President Donald Trump is undertaking the operation in Iran to ensure the Strait of Hormuz is open in the future, Trump said in a post on social media Wednesday.
"President Xi will give me a big, fat, hug when I get there in a few weeks. We are working together smartly, and very well," Trump added.
The president is expected to travel to Beijing in May to meet with President Xi Jinping.
-ABC News' Michelle Stoddart
