AS IT HAPPENED: Iranian leaders denounce negotiations; Donald Trump says he's 'highly unlikely' to prolong ceasefire; Iran will decide 'how to proceed' as ceasefire deadline looms

Thanks for joining us for our live coverage of the Middle East conflict.

Here are the key points from today, April 21.

- US President Donald Trump said he would not renew the ceasefire with Iran if the two countries can not reach a deal by midnight on Thursday (10am Thursday AEST). He also said he would not hesitate to renew strikes if this happens.

- Iran refused to guarantee it would attend talks in Pakistan tomorrow, despite reports the US was set to send a delegation to Islamabad, once again led by Vice President JD Vance.

- White House press secretary Karoline Leavitt claimed the US was closer than ever before to making a deal with Iran, claiming it was down to the "brilliant negotiating tactics" of the president.

- The ASX had a small dip in trading today, reflecting the news in global markets, as uncertainty grows as to whether the war will actually come to an end soon.

The US has "no easy path toward success" in the war with Iran, said Malcolm Davis, Senior Analyst in Defence Strategy with the Australian Strategic Policy Institute in Canberra.

Davis told CNN's Polo Sandoval that he's not hopeful the US and Iran will come to a deal during a possible second round of negotiations in Islamabad this week, because the divide between what both countries want is too great.

"It's not a good likelihood that we will see something come out of this that will actually resolve this (conflict)," Davies said.

If talks are inconclusive, the US has two main options, Davies said: either the US will continue its naval blockade of the Strait of Hormuz, or it will "go back to war fighting mode."

There is "no guarantee that simply bombing Iran will achieve US strategic objectives," he said, adding that "there's a real risk that this war spins out of control and it doesn't really achieve anything."

He added: "The Iranians have essentially been a more resilient adversary than I think the US thought they were.

"It's a challenging situation because this conflict is not just about Iran, this has strategic implications for the wider international strategic environment."

Gholamhossein Mohseni Ejei, Head of Iran's judiciary, said Tehran must "maintain 100 per cent readiness" in case the US launches new attacks, according to a video posted by Iranian state-affiliated media Fars.

There is a "strong possibility" of more attacks, Ejei said, adding the US has not yet achieved its war objectives, despite killing many of Iran's top officials.

In a separate video posted by Fars, Ejei said Iran will respond to the US seizure of the Iranian-flagged cargo ship in the Gulf of Oman, calling it a "violation" of the ceasefire.

"The naval blockade that (the US is) talking about is undoubtedly a clear violation, and the Islamic Republic will definitely respond," he said.

Iran says it hanged a man convicted over allegedly setting fire to a mosque in northern Tehran during nationwide protests in January.

The judiciary's Mizan news agency last week identified the man as Amir Ali Mir Jafari.

There was no immediate information about Jafari among activists who follow Iran.

Iran has been accused of repeatedly holding closed-door trials against suspects who can't challenge the evidence placed against them.

Iran already has hanged people from the January protests, something that US President Donald Trump had described as a red line before the recent war.

Australia's share market ended slightly lower today, as uncertainty grew surrounding the fate of the Iran war.

With US President Donald Trump giving conflicting statements as to whether the war will come to an end soon, investors have reacted somewhat nervously, with the ASX falling 3.90 points today.

This has been reflected in markets around the world, including in Asia and the United States.

Financial markets have experienced vicious swings, both up and down, since the war began due to uncertainty about its duration.

The fear is that a long-term disruption could keep so much oil and natural gas off global markets that it creates a punishing wave of inflation for the global economy.

Reported with Associated Press

The USA is reportedly closer than ever before to making a deal with Iran, according to White House Press Secretary Karoline Leavitt.

Speaking on Fox News, she said: "The United States has never been closer to making a truly good deal — unlike the horrific deal signed by Barack Hussein Obama — than we are right now.

"Why? Thanks to President Trump's brilliant negotiating tactics and the success of Operation Epic Fury."

She added that even if a deal wasn't reached, President Trump had "a number of options" to choose from.

Only time will tell if Leavitt's confident assertion will come to pass, but the ceasefire between Iran and the USA expires on Thursday morning AEST.

It has been reported a US delegation, once again led by Vice President JD Vance, will head to Islamabad, Pakistan for a fresh round of peace talks.

Trump has said if a deal is not reached, he will not renew the ceasefire.

Several funerals have been held in Lebanon for people killed in Israeli strikes, with the government claiming close to 2400 people have been killed in the past six weeks.

Photos captured by AP show several people being laid to rest in the town of Bazouriyeh, with some coffins draped in the Hezbollah flag.

Some of the people who died were civilians, while others were Hezbollah fighters.

Lebanon's government said 2387 people have been killed since Israel began strikes on southern Lebanon six weeks ago, and that more than 7600 people have been wounded.

There may be two crucial by-elections in the eastern states coming up, but opposition leader Angus Taylor has jetted off to Western Australia today.

He has called on the government to increase exploration for oil and gas deposits within Australia, claiming the current crisis has highlighted significant shortfalls.

"Whether it's existing basins where there's more potential, or new basins, like the Taroom or the Beetaloo, we know they are there, but we've got to get the incentives right to get those explorers out there exploring to get the oil and gas companies drilling and to make sure Australian oil and gas is working hard for Australians," he said.

"The best stock of fuel is the stock of fuel that you can be taking out from under the ground ... that's not 30 days of stocks. That's 30 years plus of stocks."

Vice President JD Vance is expected to leave Washington today to travel to Pakistan with top US officials to take part in the latest round of talks on the war with Iran, people familiar with the plans told CNN.

A second round of talks between the US and Iranian delegations is currently planned for Wednesday in Islamabad, they said, but they noted that the situation remains fluid due to continued heated public rhetoric by both the US and Iranians.

The White House told CNN there is no formal word on timing but added, "We expect the delegation to be on the road soon but unclear when."

The delegation is traveling to Islamabad as Trump's Wednesday (Thursday morning AEST) evening ceasefire deadline nears.

Trump said it's "highly unlikely" he would extend the ceasefire further if a deal is not reached.

Iran's Foreign Ministry condemned the seizure of Iranian cargo ship Touska by US forces and called for the "immediate release of the Iranian vessel, its sailors, crew and their families".

The US Navy fired on and seized the Iranian-flagged ship Sunday after it tried to get past the US naval blockade in the Gulf of Oman, according to President Donald Trump.

Footage released by the military showed a guided-missile destroyer firing on the vessel and Marines rappelling from helicopters onto its deck.

Iran previously vowed to retaliate for the seizure of the ship, which the Foreign Ministry called "extremely dangerous" and "criminal" in its statement.

"There is no doubt that the Islamic Republic of Iran will use all its capacities to defend Iran's national interests and security and to safeguard the rights and dignity of its citizens," the statement said.

"It is also clear that full responsibility for any further escalation in the region lies with the United States."

It is not clear how many people were aboard the ship and whether they are Iranian. CNN has reached out to US Central Command for comment on the nationality of the crew and the status of the cargo ship.