The U.S. and Iran failed to reach a deal to end their war after marathon talks in Islamabad concluded Sunday, casting doubt on a fragile cease-fire.

Each side blamed the other for the ⁠failure of the 21-hour negotiations to end fighting that has killed thousands and ⁠sent global oil prices soaring since it began over six weeks ago.

"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," Vice President JD Vance, the head ​of the U.S. delegation, told reporters shortly before he left Islamabad.

"So we go ​back ⁠to the United States, having not come to an agreement. We've made very clear what our red lines are."

The U.S. and Iranian delegations have left Islamabad to return home, Pakistani sources told Reuters.