The US said it launched new strikes on southern Iran on Monday, targeting Iranian missile sites and boats attempting to place mines.

The strikes were in "self-defence" and designed "to protect our troops from threats posed by Iranian forces", US Central Command (Centcom) said in a statement.

Iran's Islamic Revolutionary Guard Corps (IRGC) said on Tuesday it had downed a US drone and fired at a fighter jet and another drone that entered Iranian airspace, state media reported. It did not specify when this happened.

It added that Iran had the "legitimate and definite" right to retaliate against any US ceasefire violations.

"US forces conducted self-defence strikes in southern Iran today to protect our troops from threats posed by Iranian forces," Centcom spokesperson Capt Tim Hawkins said in a statement on Monday.

"US Central Command continues to defend our forces while using restraint during the ongoing ceasefire."

The US strikes targeted an area near Bandar Abbas, a southern port city and home of an Iranian naval base that sits on the Strait of Hormuz, the New York Times quotes a senior military official as saying.

Iranian state media had earlier reported that local officials in Bandar Abbas were investigating after explosions were heard.

It is unclear what impact the latest US strikes will have on any potential peace agreement between the US and Iran.

Following the US attack, Secretary of State Marco Rubio said a deal was still possible and pointed to talks on Tuesday between Iran's top negotiator and foreign minister and Qatar's prime minister.

"We'll see if we can make progress. I think it's a lot of talking back and forth going on about specific language in the initial document, so it'll take a few days," Rubio told reporters during an official visit to India.

He said President Donald Trump had "expressed his desire to make it".

"He's either going to make a good deal or no deal," Rubio said.

Asked again later about Monday's strikes, Rubio said: "The straits have to be open.

"They're going to be open one way or the other, so they need to be open.

"What's happening there is unlawful, it's illegal, it's unsustainable for the world, it's unacceptable."

Meanwhile, Iran's Supreme Leader Mojtaba Khamenei said the Middle East "will no longer serve as shields for US bases".

Khamenei, who has not been seen in public since succeeding his late father as supreme leader earlier this year, made the comments on Tuesday in a message marking the annual Hajj pilgrimage.

He added: "In addition to no longer having a safe haven for evil and establishing military bases in the region, America is moving away from its previous status day by day."

At the weekend, Trump had suggested the sides were close to a deal, but later said he had instructed negotiators "not to rush into" one, while Rubio had said an agreement could possibly be reached on Monday.

But Iranian foreign ministry spokesman Esmail Baghaei responded: "It is correct to say that we have reached a conclusion on a large portion of the issues under discussion... But to say that this means the signing of an agreement is imminent - no-one can make such a claim."

The memorandum of understanding being discussed reportedly involves a 60-day ceasefire extension, the reopening of the Strait of Hormuz and a plan for further negotiations over Iran's nuclear programme.

CBS, the BBC's US partner, has reported that American intelligence believes Iran's new supreme leader is holed up in an undisclosed location, making communication with his envoys difficult and therefore delaying the pace of talks with the US.

Mojtaba Khamenei is thought to have been injured in an Israeli strike that killed his father and predecessor on the first day of the war more than three months ago.

According to US media, the discussions will not immediately lead to a final settlement. Contentious issues will likely be negotiated later, including details of Iranian sanctions relief, the release of frozen Iranian funds, and US demands for Iran to curb its nuclear ambitions.

The International Atomic Energy Agency (IAEA) estimated that at the start of the war, Iran had about 440kg (970 lbs) of uranium enriched up to 60% purity.

This is a short process away from being enriched to the weapons-grade 90%, which theoretically could allow it to create a nuclear bomb.

On Monday night, Trump said the enriched uranium would either be "immediately" turned over to the US, or "preferably, in conjunction and co-ordination with the Islamic Republic of Iran, destroyed in place".

US and Iranian forces have observed a ceasefire since 8 April. Iran has maintained controls on Gulf shipping through the Strait of Hormuz and the US Navy has sought to blockade Iran's ports.

The US and Israel launched wide-ranging strikes on Iran on 28 February, sparking conflict across the Middle East.

Iran responded by attacking Israel and US-allied states in the Gulf, and effectively closed the Strait of Hormuz. The move sent oil prices soaring globally.

An earlier version of this story quoted the New York Times attributing detail about the reported Bandar Abbas strike to Captain Tim Hawkins, but this reference has been changed to reflect the paper's latest reporting.

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