ERBIL, Kurdistan Region of Iraq - US President Donald Trump on Tuesday said negotiations between Washington and Tehran are “moving along very nicely,” warning that Iran would get hit “really hard” if a deal is not reached to reopen the vital Strait of Hormuz “soon”.

Speaking to reporters about how negotiations with Iran are proceeding, Trump said: “We’re moving along very nicely. We’ll find out. We’ll know in 48 hours.”

A day earlier, Trump said talks with Iran were ongoing and that officials were working to reopen the Strait of Hormuz “literally tomorrow.” He previously said a potential deal with Iran would include the immediate reopening of the strategic waterway.

The two warring sides have paused hostilities on multiple occasions to pursue negotiations, only to return to violence shortly after.

“If they back out again, they're gonna get hit really hard, you know, they know that. They understand that I have no choice. They can't have nuclear weapons. Very simple,” Trump said in an interview with Fox News.

“They wouldn't be talking if we weren't doing what we're doing. We hit them very very hard, but the hard hit is yet to come and hopefully we won't have to use it. I hope we won't have to - we’re having very good discussions,” he added.

Tehran and Washington reached a memorandum of understanding (MoU) on June 17, but the deal fell apart only 21 days later after the US Central Command (CENTCOM) said Iranian forces had attacked a Cyprus-flagged ship in the Strait of Hormuz.

As a means in its war against the US and Israel, Iran has closed the Strait of Hormuz, a key waterway responsible for the transport of roughly 20 percent of the world’s oil, sharply driving up global oil prices.

The free navigation of the waterway is one of Washington’s main demands and has been a key sticking point as Iran has maintained that it has the rights over managing the strait with its coastal neighbour Oman.

On Tuesday, Axios, citing two regional sources and one US official, reported that the US, Iran, and Oman are closing in on an interim agreement to reopen the strait, with the US aiming for an announcement on Wednesday.