US Vice President J. D. Vance said that high-level negotiations between the United States and Iran ended without an agreement after more than 20 hours of talks in Islamabad, marking a significant setback in diplomatic efforts.

“We have been at it now for 21 hours, and we’ve had a number of substantive discussions with the Iranians. That’s the good news. The bad news is that we have not reached an agreement,” Vance told reporters early Sunday.

He stressed that Washington had clearly communicated its terms, but Tehran chose not to accept them. “We’ve made very clear what our red lines are… and they have chosen not to accept our terms,” he said.

Vance reiterated that the United States’ primary objective remains preventing Iran from acquiring nuclear weapons capability. He emphasized the need for a long-term and verifiable commitment from Tehran, rather than temporary assurances.

“The simple fact is that we need to see an affirmative commitment that they will not seek a nuclear weapon… not just now, not just two years from now, but for the long term,” he said, adding that such assurances were not achieved during the talks.

Despite the breakdown, Vance described the US approach as flexible and conducted in good faith under the direction of President Donald Trump. He noted that negotiators remained in constant contact with the President and the broader national security team throughout the discussions.

“I think that we were quite flexible… The President told us to come here in good faith and make our best effort to get a deal,” Vance said.

He confirmed that Washington has now presented what it considers its “final and best offer,” leaving the next move to Iran.

The failed talks underscore ongoing challenges in resolving disputes over Iran’s nuclear programme, including disagreements on verification mechanisms, sanctions relief, and limits on uranium enrichment. The outcome raises fresh uncertainty over the future of diplomatic engagement between the two sides.