US President Donald Trump has threatened to take out Iran in one night if it fails to make a deal before the deadline he set for Tehran to reopen the Strait of Hormuz, a critical global energy route.

Trump's deadline for an acceptable deal - one that includes the free flow of energy through the Gulf - is set for 20:00 EDT (01:00 GMT) on Tuesday.

Speaking at the White House on Monday, Trump said that he believed reasonable leaders in Iran were negotiating in good faith, but the outcome remained uncertain.

Iran has so far rejected proposals for a ceasefire, and has instead called for an immediate end to hostilities, post-conflict reconstruction and the lifting of sanctions.

Trump's news conference held alongside General Dan Caine, the chairman of the Joint Chiefs of Staff, comes days after US forces successfully recovered two crew members of an F-15 fighter jet that was downed in southern Iran.

While much of Trump's remarks highlighted what he described as the heroic rescue of the crew, he once again repeated his warning that the US could launch attacks on Iran's energy and transportation infrastructure if the Strait of Hormuz was not reopened by Tuesday's deadline.

The entire country can be taken out in one night – and that night might be tomorrow night, he stated, asserting that once the deadline passes, Iran would be sent back to the Stone Ages.

Despite Iran's earlier rejection of US demands, Trump continued to express optimism that Iran was negotiating in good faith after successive layers of Iranian leadership were killed in US and Israeli strikes.

We're going to find out, he said.

Legal experts have warned that deliberate, sustained assaults on Iranian infrastructure could constitute a war crime, adding a layer of complexity to the ongoing negotiations amid fears of escalation.