Top negotiator Mohammad Bagher Ghalibaf says US naval blockade of Iran’s ports is ‘a clumsy and ignorant decision’.

Iran’s Islamic Revolutionary Guard Corps Navy (IRGC) says the Strait of Hormuz is closed and that any ship that attempts to pass through the waterway will be targeted, a dramatic reversal less than 24 hours after the critical shipping lane was reopened.

In a statement carried by Iran’s Student News Agency, the IRGC navy said on Saturday the strait will be closed until the United States lifts its naval blockade on Iranian vessels and ports. It said the blockade was a violation of the ongoing ceasefire agreement in the US-Israel war on Iran.

“We warn that no vessel of any kind should move from its anchorage in the Persian Gulf and the Sea of Oman, and approaching the Strait of Hormuz will be considered cooperation with the enemy, and the offending vessel will be targeted,” it said.

Mohammad Bagher Ghalibaf, Iran’s parliament speaker and a senior negotiator in talks between Washington and Tehran on ending the war, said in a television interview that “the Strait of Hormuz is under the control of the Islamic Republic”.

“The Americans have been declaring a blockade for several days now. This is a clumsy and ignorant decision,” he added.

The reassertion of control came just hours after Iran had briefly reopened the strait, in line with a 10-day ceasefire between Israel and Lebanon. Oil prices dropped on global markets after Iranian Foreign Minister Abbas Araghchi said on Friday that the waterway was “completely open for all commercial vessels.”

More than a dozen commercial ships passed through the waterway before the IRGC reversed course.

Iranian gunboats reportedly fired on two commercial ships on Saturday, according to United Kingdom Maritime Trade Operations (UKMTO). India’s Ministry of External Affairs also said that two Indian-flagged ships were involved in a “shooting incident” in the strait.

Some merchant vessels in the region received radio messages from the IRGC Navy, warning that no ships were being allowed through the strait.

US President Donald Trump said Tehran could not blackmail Washington by closing the waterway and warned that he would put an end to the ceasefire if a deal before its expiry on Wednesday is not reached. Trump added that the naval blockade would “remain in full force”.

Iranian Supreme Leader Mojtaba Khamenei, meanwhile, said the navy was ready to inflict “new bitter defeats” on its enemies.

‘Two competing blockades’

Al Jazeera correspondent Zein Basravi said that Iran and the US are back where they were the previous day.

“Less than 24 hours ago, world leaders were praising what they thought was a breakthrough in this conflict, hoping Iran was signalling a confidence-building measure by opening the Strait of Hormuz, potentially leading to a ceasefire deal and a permanent end to the war,” he said.

“As disappointed as people may be, this isn’t entirely surprising. What we’re seeing now is a return to square one,” he added, saying there are now “two competing blockades in place”.

Al Jazeera’s Ali Hashem, reporting from Tehran, said Iran was using the strait to send a message.

“It’s clear that Iran is dealing with a situation in which they are not sure what’s on the table. So the Strait of Hormuz is once again the only space for engagement, even if it’s a negative engagement. And it’s the space where they are sending and conveying messages to the Americans, showing their leverage,” he said.