Vessels will still be able to transit Strait of Hormuz to and from non-Iranian ports, says CENTCOM; Iran warns any approaching military vessels will be breaching ceasefire.

The United States military has announced it will begin blockading all Iranian ports on Monday, its latest move to exert pressure on Tehran after marathon peace talks in Pakistan concluded without a deal.

In a statement on Sunday evening, US Central Command (CENTCOM) said the blockade would apply to “all maritime traffic entering and exiting Iranian ports” from 10am Eastern Time (14:00 GMT) on April 13. That includes “vessels of all nations entering or departing Iranian ports and coastal areas”, including those on the Gulf and the Gulf of Oman.

However, US forces “will not impede freedom of ⁠navigation for vessels transiting the Strait ⁠of Hormuz to and ⁠from non-Iranian ports,” CENTCOM said, in an apparent scaling back from President Donald Trump’s earlier threat to blockade the entire strait and pursue ships paying tolls to Iran.

“There are a lot of questions here,” said Al Jazeera’s Heidi Zhou-Castro from Washington, DC, pointing to “conflicting information” coming out of the US side.

“Trump said the blockade would target any and all ships trying to enter or leave the Strait of Hormuz. But CENTCOM is saying this would only target ships going to or from Iranian ports.”

The price of US crude oil jumped 8 percent to $104.24 a barrel after the US blockade threat. Brent crude oil, the international standard, increased 7 percent to $102.29.

Iran has essentially taken control over the Strait of Hormuz, a vital chokepoint for the global energy market, since the US and Israel launched a war against the country on February 28. Traffic through the waterway has since slowed to a trickle, nearly paralysing about one-fifth of the world’s oil and liquefied natural gas shipments.

Iran has continued to move its own vessels through the strait, while allowing limited passage of ships from other countries. Iranian officials have discussed setting up a toll system after the fighting ends.

In a statement responding to Trump’s blockade threat, Iran’s Islamic Revolutionary Guard Corps said any approaching military vessels would be in breach of a US-Iran ceasefire – meant to be in effect until April 22 – and “will be dealt with severely”.

The US-declared blockade appears to be triggered by the failure of the talks in Pakistan’s capital, Islamabad, raising fears of renewed fighting.

Iranian officials blamed the US side for failing to reach a deal, with Minister of Foreign Affairs Abbas Araghchi saying US negotiators shifted the “goalposts” and obstructed efforts when a memorandum of understanding was “just inches away”.

Zohreh Kharazmi, an associate professor at the University of Tehran, said the US “is not in a position to dictate” to Iranians how to behave, or “to choose which vessels may pass”.

“If this blockade becomes a contest between the resilience of the Islamic Republic and the resilience of global markets, it will not take long to see who is losing,” she said, adding that Iran “is ready for a prolonged war”.

“Technically, they [the US] cannot control the situation. With Hollywood-style strategies, they cannot prevail in this battleground.”