Iran says it temporarily closed the Strait of Hormuz — a vital international shipping route — as it entered a new round of talks with the US over its nuclear capabilities.
Iran's official reason for closing the strait, through which 20 per cent of the world's oil passes, was for "safety and maritime concerns" as it conducted live military drills.
But the unusual move was widely seen as a message to the US, which is continuing to amass enormous firepower in the region and has threatened to strike Iran if the countries cannot reach a deal.
"Clearly on the day that they're negotiating with the Americans I don't think it's a coincidence," said Sina Azodi, the director of the Middle East Studies program at George Washington University.
"Iranians for decades have been trying to portray themselves as the ones who call the shots in the Persian Gulf.
"They shut it down just to make the point that they are the ones who are calling the shots there."
Despite the potentially provocative move, both American and Iranian officials issued optimistic, albeit vague, declarations that progress had been made in the latest round of negotiations.
Pressure for a deal
Tensions between the two countries have been flaring in recent weeks.
The US wants to prevent Iran from becoming a nuclear power and has sent two aircraft carriers and accompanying warships to the region as it pressures Iran for "a deal".
Iran insists its nuclear-enrichment program is peaceful, even though it has enriched uranium far beyond the purity needed for power generation.
It wants crippling economic sanctions lifted in exchange for any concessions.
The specifics of the talks, which took place in Switzerland and were mediated by Oman, remain unknown.
"In some ways it went well," US Vice-President JD Vance told Fox News after the talks on Tuesday, local time.
"They agreed to meet afterwards. But in other ways it was very clear that the president has set some red lines that the Iranians are not yet willing to actually acknowledge and work through."
But Iranian Foreign Minister Abbas Araqchi said the two sides reached an understanding over the main "guiding principles" during the talks.
"Different ideas have been presented. These ideas have been seriously discussed. Ultimately we've been able to reach a general agreement on some guiding principles," Mr Araqchi told Iranian state media.
A US official said Iran would make detailed proposals in the next two weeks to close gaps between the two sides.
US envoys Steve Witkoff and Jared Kushner were part of the US delegation.
Omani Foreign Minister Badr Albusaidi said the talks "concluded with good progress towards identifying common goals and relevant technical issues".
Later, Iranian state media reported the Strait of Hormuz had been closed for several hours, but it was unclear if it had been reopened.
Tehran has in the past threatened to shut down the strait to commercial shipping if it is attacked, a move that would drive up crude prices.
Gunboat diplomacy or imminent strike?
The US has been warning of a sustained military campaign if it cannot reach an agreement with Iran to curb its nuclear enrichment goals.
The US's largest aircraft carrier, USS Gerald R Ford, was last week deployed to join USS Abraham Lincoln in the region.
Some analysts believe the massive scale of the military build-up near Iran suggests a US strike is inevitable. Others say US President Donald Trump could simply be exerting maximum pressure to strengthen the US's negotiation position.
"I think both are possible," Dr Azodi told the ABC.
"President Trump has taken the concept of gunboat diplomacy literally, but he also doesn't have much patience in negotiations.
"I think the experience of Venezuela and other places has given him this belief that he can strike at a very low cost, at almost no cost, and he can claim victory … so I don't think it's just a bluff."
On the eve of the talks Mr Trump said he was confident Iran wanted to do a deal.
"I don't think they want the consequences of not making a deal," he ?said on Monday.
Iranian Supreme Leader Ayatollah Ali Khamenei responded to the threat of US military action by saying: "The strongest army in the world might sometimes receive such a slap that it cannot get back on its feet."
"Of course a warship is a dangerous apparatus, but more dangerous than the warship is the weapon that can sink the warship," he said, according to Iranian state TV.
He also warned the US against "forcing the result of talks in advance".
ABC/AP/Reuters
