US military is poised to blockade Iranian ports, while Tehran threatens ports in the Mideast

It was not clear if the blockade had started when the designated time of 10 a.m. EDT (2 p.m. GMT) arrived. Minutes earlier, a notice to mariners issued by the United Kingdom Maritime Trade Operations agency, which monitors maritime security, said the restrictions included “the entirety of the Iranian coastline, including ports and energy infrastructure.”

The notice added that transit through the strait “to or from non-Iranian destinations is not reported to be impeded by these measures,” but it added that ships “may encounter military presence” in the strait.

Iran’s effective closure of the strait, through which 20% of traded oil passes in peacetime, has sent oil prices skyrocketing, pushing up the cost of gasoline, food and other basic goods far beyond the Middle East. Tehran has allowed some ships perceived as friendly to pass while charging considerable fees, leading to accusations it is holding the global economy hostage.

Some analysts are doubtful that the U.S. can restore normal shipping through force alone — and it’s not clear how a blockade would work or what the dangers might be to U.S. forces. The question is essentially who can endure the most pain: Could a blockade make Iran’s economic situation untenable and force it to concede? Or will it drive global oil and other prices so high that U.S. President Donald Trump is forced to back down?

The blockade could have far-reaching effects

The U.S. military's Central Command announced that the blockade would be enforced “against vessels of all nations entering or departing Iranian ports and coastal areas.” It said that would include all of Iran’s ports on the Persian Gulf and Gulf of Oman.

CENTCOM's decision to allow ships traveling between non-Iranian ports to transit the strait was a step down from Trump’s earlier threat to blockade the waterway.

In a social media message posted shortly after the blockade was due to begin, Trump said Iran’s navy was “laying at the bottom of the sea, completely obliterated,” but he added that Tehran still has “fast attack ships,” and warned that “if any of these ships come anywhere close to our BLOCKADE, they will be immediately ELIMINATED."

Iran issued threats of its own.

“Security in the Persian Gulf and the Sea of Oman is either for everyone or for NO ONE,” the Islamic Republic of Iran Broadcasting reported Monday. “NO PORT in the region will be safe,” read a statement from the Iranian military and the Revolutionary Guard.

The threats halted the limited ship traffic that resumed in the strait since the ceasefire, according to a report from Lloyd’s List Intelligence. Marine trackers say over 40 commercial ships have crossed since the start of the ceasefire last week, down from roughly 100 to 135 vessel passages per day before the war.

The blockade is likely intended to pile pressure on Iran, which has exported millions of barrels of oil since the war began, much of it likely carried by so-called dark transits that evade Western sanctions and oversight.

But the effects will be felt far beyond Iran. The price of Brent crude oil, the international standard, rose 7% to hover around $102 per barrel on Monday. It cost roughly $70 per barrel before the war.

Israeli Prime Minister Benjamin Netanyahu, who has come under domestic criticism for the inconclusive outcome of the war, expressed support Monday for Trump’s “strong stance to impose a naval blockade on Iran.”

In Spain, where Prime Minister Pedro Sánchez has been Europe’s loudest critic of U.S. and Israeli military actions in the Middle East, Defense Minister Margarita Robles slammed the blockade.

“Since the war began, everything has been senseless,” Robles told Spanish broadcaster TVE on Monday. She said the threatened blockade “is just another episode of the downward spiral we have been dragged into.”

Iran says ‘if you fight, we will fight'

Top-ranking Iranian officials threatened retaliation.

Ebrahim Rezaei, a spokesperson for the Iranian parliament’s National Security Commission, dismissed U.S. warnings of a potential blockade as “more bluffing than reality,” while warning that Tehran was prepared to respond if the situation escalates militarily.

“It will make the current situation (Trump) is in more complicated and makes the market — which he is angry about — more turbulent. And we may also reveal other cards that we have not used in the game,” he said in a post on X.

The Iranian parliament speaker, Mohammad Bagher Qalibaf, addressed Trump in a statement: “If you fight, we will fight.”

Ceasefire is holding but shaky after talks end without agreement

The blockade threat came after marathon U.S.-Iran ceasefire talks in Pakistan ended without an agreement on Saturday.

U.S. Vice President JD Vance said the talks stalled after Iran refused to accept American terms on refraining from developing a nuclear weapon.

Iran has insisted its nuclear program is peaceful. However, it has pushed forward with steps that could give it the ability to build a nuclear weapon, including enriching uranium to near weapons-grade levels and developing long-range missiles potentially capable of delivering a bomb.

Iranian negotiators could not agree to all U.S. “red lines,” said a U.S. official who spoke on condition of anonymity because they were not authorized to describe positions on the record. Those red lines included never obtaining a nuclear weapon, ending uranium enrichment, dismantling major enrichment facilities and allowing retrieval of its highly enriched uranium, along with opening the strait and ending funding for its armed proxies in the region: Hamas, Hezbollah and the Houthis.

Iran’s ambassador to India, Mohammad Fathali, said the main sticking points for Tehran were its nuclear program, war reparations and sanctions relief.

Neither Iran nor the U.S. have indicated what will happen after the ceasefire expires on April 22. The fighting has killed at least 3,000 people in Iran, 2,055 in Lebanon, 23 in Israel and more than a dozen in Gulf Arab states, and damaged infrastructure in half a dozen countries.

Pakistani Foreign Minister Ishaq Dar said his country will try to facilitate a new dialogue in the coming days.

Turkish Foreign Minister Hakan Fidan, whose country has supported mediation efforts, suggested that the ceasefire could be extended for 45 to 60 days to allow for more negotiations.

Corder reported from The Hague, Netherlands, Frankel from New York. Associated Press writers Melanie Lidman in Tel Aviv, Israel; Collin Binkley and Ben Finley in Washington; Kareem Chehayeb in Beirut; Sheikh Saaliq in New Delhi; Jill Lawless in London; and Ghaya Ben MBarek in Tunis, Tunisia, contributed to this report.