The move comes after marathon ceasefire negotiations between the U.S. and Iran in Pakistan, which ended without agreement and set the stage for renewed escalation. Iranian leaders signaled they would respond to the blockade.
The U.S. military’s Central Command (CENTCOM) announced the blockade would cover all Iranian ports, starting Monday at 10 a.m. Eastern time (4:30 p.m. in Iran), and would be “impartially enforced against vessels of all nations.”
CENTCOM stated it would still allow passage through the strait for ships traveling between non-Iranian ports, a softening from Trump’s earlier threat of a full strait blockade.
The blockade announcement halted the limited shipping traffic that had resumed in the strait following the ceasefire, according to an early report from Lloyd’s List Intelligence. Marine tracker data showed over 40 commercial vessels had transited the strait since the ceasefire began, compared to a pre-war daily average of roughly 100 to 135 vessels.
Later on Sunday, Trump escalated his public feud over the war with Pope Francis, sharply attacking him in a Truth Social post calling the Catholic leader “terrible on foreign policy.” The unusually harsh broadside came after the Pope condemned the war and urged political leaders to stop fighting and negotiate peace.
The blockade is likely intended as additional pressure on Iran, which has exported millions of barrels of oil since the war began, much of it likely via so-called “dark” transits evading sanctions and Western government monitoring.
Trump is also seeking to undermine Iranian control of the Strait of Hormuz after demanding Tehran reopen the passage, through which 20% of global oil flowed before hostilities. The U.S. blockade could further rattle world energy markets.
Oil prices rose in early trading following the blockade announcement. U.S. crude rose 8% to $104.24 a barrel, while Brent, the international benchmark, rose 7% to $102.29. Brent traded around $70 a barrel in late February before the war.
A series of high-ranking Iranian officials threatened retaliation. Mohsen Rezaei, a military advisor and former Revolutionary Guard commander, posted on X that Iran’s armed forces have “major, yet unused levers” to respond to a Hormuz blockade. He warned Iran would not be forced into moves by “Twitter messages and imaginary plans.”
Iranian parliamentary speaker Mohammad Bagher Qalibaf, who led Iran’s negotiation delegation, addressed Trump in a statement upon returning to Iran: “If you fight, we will fight.”
Iran’s Revolutionary Guard later stated the strait remains under Iran’s “full control” and open to civilian, non-designated military vessels, while military ships, according to two semi-official Iranian news agencies, would receive a “forceful response.”
During the 21-hour talks this weekend in Pakistan, the U.S. military announced two destroyers had transited the strait to begin mine-clearing operations, the first such passage since the war began. Iran denied this.
The face-to-face negotiations, concluding in the early hours of Sunday, were the highest-level political talks between the long-time rivals since the 1979 Islamic Revolution.
Trump stated Tehran’s nuclear ambitions were a primary reason for the talks’ failure. In a Fox News comment, he again threatened attacks on civilian infrastructure if Iran does not abandon its nuclear program.
“In half a day they wouldn’t have a single bridge standing, they wouldn’t have a single power plant, and they’d be back in the Stone Age,” Trump said.
Vice President JD Vance, who led the U.S. delegation, said Washington would need a “clear commitment that they will not seek nuclear weapons.”
Iranian negotiators could not agree to all U.S. “red lines,” said a U.S. official speaking anonymously as they were not authorized to discuss negotiation positions. Those red lines included Iran never possessing nuclear weapons, halting uranium enrichment, dismantling key enrichment facilities, surrendering its highly enriched uranium, reopening the Strait of Hormuz, and ending funding for Hamas, Hezbollah, and Houthi rebels.
Iranian officials said the talks failed over two or three key points, accusing the U.S. of excessive demands. Qalibaf, who noted some progress in talks, signaled it was time for the United States to “decide whether they can earn our trust or not.”
Iran’s foreign minister claimed the United States derailed the talks when they were “inches” from a deal but offered no evidence for the assertion.
“We faced maximalism, moving goalposts, and obstruction,” wrote Abbas Araghchi on X.
Neither Iran nor the U.S. indicated what would happen after the ceasefire expires on April 22.
Pakistani Foreign Minister Ishaq Dar said his country would attempt to facilitate a new round of dialogue in the coming days. Iran, according to the state news agency IRNA, signaled it was open to continuing talks.
Iran’s nuclear program has long been central to tensions, even before the U.S. and Israel launched the war on February 28. Fighting so far has killed at least 3,000 in Iran, 2,055 in Lebanon, 23 in Israel, and over ten in Gulf states, with infrastructure damaged in at least six countries.
Tehran has long denied wanting to develop nuclear weapons, insisting on its right to a civilian nuclear program. Achieving the historic 2015 nuclear deal, from which Trump later withdrew the U.S., required months of multiple negotiation rounds. Experts note Iran’s stockpile of enriched uranium, while not yet weapons-grade, is only short technical steps away.