The U.S. military blockade of all of Iran‘s ports and coastal areas came into effect at 10 a.m. Monday.
President Donald Trump announced the naval blockade Sunday in the wake of negotiations between the U.S. and Iran in Pakistan that concluded without a deal to end the conflict. The U.S. wants a commitment from the Islamic republic that it will not develop a nuclear weapon, a condition Iranian representatives have balked at.
According to a social media post from U.S. Central Command (CENTCOM), the blockade is enforced impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including all Iranian ports on the Persian Gulf and Gulf of Oman.
Related Stories
Iran’s armed forces said no port in the Persian Gulf or the Gulf of Oman would be safe if its ports are threatened, and that any blockade of vessels would be considered an “act of piracy.”
More than 15 U.S. warships are in place in the Middle East to support the operation, a senior U.S. official told the Wall Street Journal.
An advisory from the U.K. Maritime Trade Operations (UKMTO) Centre to mariners said transit passage through the Strait of Hormuz to or from non-Iranian destinations is not expected to be impeded by the blockade. However, vessels may encounter military presence, directed communications or “right-of-visit” procedures during passage.
Over the weekend, vessel crossings through the Strait of Hormuz rose to 14 on each day, matching the previous peak seen on April 3, according to ship tracking intelligence firm MarineTraffic. Most weekend crossings were east-to-west, with half of the vessels operating outside the sanctioned and shadow fleets.
“Traffic remains far below the pre-conflict norm of roughly 100 transits per day, reinforcing that this is still a constrained operating environment rather than any meaningful normalization,” said Ana Subasic, trade risk analyst at MarineTraffic in a Monday update. “The weekend breakdown in U.S.-Iran talks appears to have effectively derailed the ceasefire framework…that leaves the market facing a more restrictive and legally uncertain transit regime, rather than a reopening.”
According to Subasic, the primary uncertainty now is operational, namely regarding how any U.S. military enforcement measures are applied at sea, and whether currently permissible movements remain viable once those restrictions begin to take effect.
The blockade comes as the U.S. and Iran are in the middle of a two-week ceasefire agreed upon last Tuesday. But despite the ceasefire being contingent on the opening of the Hormuz strait, Iran’s Islamic Revolutionary Guard Corps (IRGC) had still maintained that vessels would still need its permission to pass through.
The IRGC Navy had also reportedly established a “toll booth” system for ships seeking passage ahead of the ceasefire, with the country also threatening that it has placed mines throughout the strait.
In his Truth Social post announcing the blockade, President Trump touched on potential U.S. responses to both concerns in the oil conduit.
“At some point, we will reach an ‘ALL BEING ALLOWED TO GO IN, ALL BEING ALLOWED TO GO OUT’ basis, but Iran has not allowed that to happen by merely saying, ‘There may be a mine out there somewhere,’ that nobody knows about but them,” Trump said. “I have also instructed our Navy to seek and interdict every vessel in International Waters that has paid a toll to Iran. No one who pays an illegal toll will have safe passage on the high seas. We will also begin destroying the mines the Iranians laid in the Straits.”
Following Trump’s call for a blockade, the IRGC said military vessels attempting to approach the strait “under any pretext” would be considered a violation of the ceasefire.
China, which Trump threatened to slap with another 50 percent tariff due to its supply of weapons to the country, said the conflict must stop as soon as possible.
“Keeping the area safe and stable and ensuring unimpeded passage serves the common interest of the international community,” said China’s Foreign Ministry spokesperson Guo Jiakin Monday morning. “The root cause of the disruption at the Strait of Hormuz is the military conflict.”
Vessels that were tentatively gearing up to exit as peace talks were underway are already turning back around. MarineTraffic highlighted that two oil tankers, the Rich Starry and the Ostria, reversed course Monday morning after approaching the chokepoint.
Other container ships closer to the strait’s entrance appear to be idling. The 2,800 20-foot equivalent unit (TEU) vessel CMA CGM San Antonio that had turned its transponder off inside the Persian Gulf since March 2 appeared again on April 9, according to information cited by Destine Ozuygur, a senior market analyst at freight rate benchmarking company Xeneta. The vessel most recently departed from the U.A.E.’s Port of Jebel Ali, broadcasts India’s Mundra Port as its next destination and is currently lingering near the strait.
“The vessel is now idling north of Sharjah Port with five other CMA CGM owned vessels, including the CMA CGM Manaus that is broadcasting ‘Indian crew and vsl’ in what was likely preparation for an Iran-approved exit before the blockade announcement,” Ozuygur said.
As the concerns regarding the Hormuz linger, CMA CGM has again changed its mind on bringing services back to the Red Sea.
After an about-face to a Red Sea return in the weeks ahead of the war, CMA CGM is bringing the Mediterranean Club Express (MEX) service back to use the Suez Canal route.
The MEX service is the second such Asia-to-Mediterranean Sea service sailing the Suez, with the company braving the Red Sea crisis through the Phoenician Express (BEX2) weekly loop since July 2024. MEX was one of three services using the alternative Cape of Good Hope route that had previously been tested on a Red Sea route at the turn of the year.
Two ships on eastbound voyages have already switched from the Cape route to the Suez route since the end of last month, starting with the 16,022-TEU CMA CGM Jules Verne on March 29 followed by the 15,536-TWU CMA CGM Apollon on April 3. The first westbound voyage is scheduled on April 21 with the 16,022-TEU CMA CGM Marco Polo.
