US Vice President JD Vance said Sunday that Washington and Tehran have not yet reached an agreement as high-stakes US and Iran talks concluded without a breakthrough in Islamabad.

"We have been at it now for 21 hours, and we have had a number of substantive discussions, that’s the good news. 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 told US journalists at a hotel where the American and Iranian delegations have been are holding talks since Saturday.

"They have chosen not to accept our terms," he added.

He said Washington has not seen a "long-term" Iranian commitment to forgo developing nuclear weapons

"The simple question is do we see a fundamental commitment of will for the Iranians not to develop a nuclear weapon, not just now, not just two years from now, but for the long term. We haven't seen that yet," said Vance.

He abruptly wrapped up his short news conference and walked away, ignoring questions about the Strait of Hormuz and whether the failure of the negotiations means the US is headed back to war.

Iranian state media, IRIB, reported late Saturday that Iran and the US had agreed to hold another round of talks Sunday in Pakistan, following a proposal by Pakistani mediators.

"We leave here, and we leave here with a very simple proposal, a method of understanding that is our final and best offer. We'll see if the Iranians accept it," said Vance.

He appreciated Pakistani Prime Minister Shehbaz Sharif and Army chief Gen. Asim Munir for mediating and "trying to bridge the gap" between Washington and Tehran, adding that “whatever shortcomings were in the negotiations were not because of the Pakistanis."

Responding to a question about what the Iranians rejected, he said, “I won’t go into all the details because I don't want to negotiate in public after we have negotiated for 21 hours in private. But the simple fact is that we need to see an affirmative commitment that they will not seek a nuclear weapon and that they will not seek the tools that would enable them to quickly achieve a nuclear weapon.”

Asked whether Iranian frozen assets were discussed during negotiations, Vance avoided replying directly, saying, “We talked about all those issues, and we talked about a number of issues beyond that. And so, certainly those things came up. But again, we just could not get to a situation where the Iranians were willing to accept our terms.”

Vance left Islamabad after the news conference. Earlier, a Pakistani source told Anadolu that Vance extended his stay in Pakistan to take part in the talks that have stretched into a second day.

In a related development, the spokesperson for Iranian Ministry of Foreign Affairs, Esmaeil Baqaei, said that "numerous" messages and texts have been exchanged between the two sides during a "busy and long day.”

“In the past 24 hours, discussions were held on various dimensions of the main negotiation topics, including the Strait of Hormuz, the nuclear issue, war reparations, lifting of sanctions, and the complete end to the war against Iran and in the region,” he wrote on US social media platform X.​​​​​​​

“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 also expressed appreciation to the “government and the warm-hearted and noble people of the Islamic Republic of Pakistan for hosting the negotiations and their benevolent efforts in advancing this process.”

Pakistani hosted the talks as part of efforts to end the broader regional conflict under a fragile two-week ceasefire brokered earlier this week. (Anadolu Agency, excluding headline)