Serious differences remain in talks on resuming compliance with the 2015 Iran nuclear deal and if they cannot be bridged in the foreseeable future, Washington will need to rethink its approach, a senior US official said on Thursday.
"This process is not going to be open forever," the senior US official told reporters.
"We do have differences and if we can't bridge them in the foreseeable future, I think we are going to have to regroup and figure out how we ... move ahead."
The comments come after departing Iranian President Hassan Rouhani said on Wednesday that US sanctions on Iran could be coming to an end soon.
Addressing the Cabinet and the Iranian people, Mr Rouhani spoke about the ongoing nuclear talks and claimed that "the government has done a great job and ended the [economic] war".
But the US official repeated Washington's caution that more work remains to be done.
"Nothing is agreed until everything is agreed," the official said, adding, "we are not there yet."
"We are still negotiating every issue, whether it’s the scope of sanctions, the scope of the steps that Iran will take to come back in compliance with its nuclear obligations. ... We need to continue negotiating to see if we can reach a comprehensive package that will be satisfactory."
The sixth round of indirect talks adjourned on Sunday, two days after hard-liner Ebrahim Raisi, the Iranian judiciary chief who is subject to US sanctions, was elected president of the Islamic Republic. He is due to take office in August.
The US official, who spoke to reporters on condition he not be named, said the US delegation expected to return to Vienna for a seventh round of talks in the not-too-distant future but that he did not know when.
Iran struck a deal with major powers in 2015 to curb its uranium enrichment program, a possible pathway to nuclear arms, in return for the lifting of US, EU and UN sanctions.
Then-president Donald Trump abandoned the deal in 2018 and reimposed harsh sanctions, prompting Tehran to start violating some of the nuclear limits in 2019 while sticking to its position that it had no nuclear weapons ambitions.
President Joe Biden is seeking to revive the agreement.
