US Secretary of State Marco Rubio has said preventing Iran from acquiring a nuclear weapon remains the central concern in any potential agreement, amid renewed diplomatic efforts.

In a Fox News interview, Rubio responded to Iran’s latest proposal, which suggests easing restrictions on the Strait of Hormuz in exchange for lifting the US blockade and ending the war, while deferring talks on Tehran’s nuclear programme.

“There’s no doubt in my mind that at some point in the future, if this radical clerical regime remains in charge in Iran, they will decide they want a nuclear weapon,” Rubio said.

“That fundamental issue still has to be confronted. That still remains the core issue here,” he added.

Questioned about Iran’s intentions, Rubio said Tehran is a “skilled negotiator” seeking to buy time, stressing that any agreement must ensure Iran cannot move toward developing nuclear weapons.

“We can’t let them get away with it,” he said. “Any agreement must definitively prevent them from sprinting towards a nuclear weapon at any point.”

Meanwhile, US Treasury Secretary Scott Bessent warned countries against engaging with Iranian airlines following the resumption of commercial flights.

In a statement, Bessent said providing services such as jet fuel, maintenance or landing support to Iranian carriers could expose third parties to US sanctions.

He also claimed that Iran’s oil industry is under increasing pressure due to the US blockade, warning that production could decline further, potentially leading to gasoline shortages.

The developments come as tensions persist between Washington and Tehran despite a fragile ceasefire, with key disagreements—particularly over Iran’s nuclear programme—remaining unresolved.