Islamabad, Pakistan - Peace talks between the US and Iran ended without reaching an agreement, Vice President JD Vance announced on Sunday.

The negotiations, held in Islamabad with Pakistani officials acting as mediators, began on Saturday and were aimed at reaching a lasting settlement to the six-week-old unprovoked war started by the US and Israel.

Vance said the talks lasted for 21 hours but that he was returning to the US without an agreement.

"We've had a number of substantive discussions with the Iranians. That’s the good news," he said at a brief press conference.

"The bad news is that we have not reached an agreement, and I think that’s bad news for Iran much more than it’s bad news for the United States of America," Vance said.

"We’ve made very clear what our red lines are, what things we’re willing to accommodate them on, and what things we’re not willing to accommodate them on. And we made that as clear as we possibly could, and they have chosen not to accept our terms."

Vance said the US was seeking confirmation that Iran would not seek a nuclear weapon, despite repeated and unequivocal assurances that it is not.

"The simple fact is that we need to see an affirmative commitment that they will not seek a nuclear weapon, and they will not seek the tools that would enable them to quickly achieve a nuclear weapon," he said.

Shortly before Vance's press conference, Iranian Foreign Ministry spokesman Esmaeil Baqaei wrote on X that the two sides had discussed a range of issues. These included the Strait of Hormuz, nuclear issues, reparations, and the lifting of sanctions.

"The success of this diplomatic process depends on the seriousness and good faith of the opposing side, refraining from excessive demands and unlawful requests, and the acceptance of Iran’s legitimate rights and interests," Baqaei wrote.

Iranian news agencies Tasnim and Fars had earlier cited "excessive demands" by the US, identifying the Strait of Hormuz as a central sticking point to the talks.