Live updates: Follow the latest news on Iran war
The US military said it would begin a blockade of all ships entering and leaving Iranian ports at 10am Eastern Time (6pm UAE time) on Monday, after President Donald Trump announced plans for the naval operation in the Strait of Hormuz.
The blockade "will be enforced impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including all Iranian ports on the Arabian Gulf and Gulf of Oman", the US Central Command (Centcom) said in a statement.
It said US forces would not impede freedom of navigation for vessels transiting the strait to and from non-Iranian ports. Additional information will be provided to commercial mariners through a formal notice before the blockade begins, Centcom added.
An Iranian military spokesman said US restrictions on vessels in international waters were illegal and "amount to piracy". Iran will implement a "permanent mechanism" to control the strait, he said.
The spokesman added that Gulf ports must be accessible to all vessels and that no port in the Gulf or Gulf of Oman would remain secure if Iranian ports were endangered.
Mr Trump said on Sunday that the US Navy would start blockading the strategic waterway, raising the stakes after talks with Iran failed to secure a deal to end the war, jeopardising a fragile two-week ceasefire. The weekend negotiations in Pakistan's capital Islamabad were the first direct US-Iranian meeting in more than a decade and the highest-level discussions since the 1979 Islamic revolution.
In a post on social media, Mr Trump said the US would take action against every vessel in international waters that had paid a toll to Iran. He also said America would begin destroying Iranian mines in the strait, a choke point for about 20 per cent of global energy supplies that Iran has blocked since the start of the conflict in February.
"No one who pays an illegal toll will have safe passage on the high seas," Mr Trump wrote. He added that "any Iranian who fires at us, or at peaceful vessels, will be blown to hell".
Iran's Islamic Revolutionary Guard Corps responded by warning that military vessels approaching the strait would be considered a breach of the ceasefire and would be dealt with harshly, emphasising the risk of further escalation.
Iran's Parliament Speaker Mohammad Bagher Ghalibaf, who led his country's delegation at the Islamabad talks along with Foreign Minister Abbas Araghchi, said Mr Trump's latest threats would have no effect on Iran. "If you fight, we will fight, and if you come forward with logic, we will deal with logic," he said in comments reported by state media.
China on Monday called for calm and restraint on all sides. Foreign Ministry spokesman Guo Jiakun said keeping the waterway safe, stable and unimpeded served the common interests of the international community. China is ready to work with all sides to protect energy security and supplies, he added.
Blocking Iranian shipments would cut off a significant source of oil from the world's markets. Iran exported 1.84 million barrels per day of crude in March and has shipped 1.71 million bpd so far in April, compared with a full-year average of 1.68 million bpd in 2025, data from analytics company Kpler showed.
However, a surge in Iranian output before the war started on February 28 has led to near-record levels of Iranian oil loaded on ships – more than 180 million barrels as of this month, Kpler said.
Shipping traffic through the strait has effectively halted despite last week's two-week ceasefire between Washington and Tehran. Oil tankers were steering clear of the waterway on Monday.
Before the war began, most Iranian oil exports were shipped to China, the top global crude importer. Last month, the US announced a sanctions waiver that enabled other buyers, including India, to purchase Iranian oil.
India was to receive its first crude shipment from Iran in seven years, ship tracking data from LSEG and Kpler showed last week. Before the war, most oil and natural gas shipped through the strait was bound for Asia, the largest importing region.
