Vance led a delegation that met with Iranian officials in Pakistan over the weekend, but the talks ended without securing a deal to end the more than five-week US-Israeli assault against the Islamic republic.

“I really think the ball is in the Iranian court, because we put a lot on the table. We actually made very clear what our red lines were,” Vance said in an interview with Fox News.

“There are two things in particular where the president of the United States really said we have no flexibility,” Vance said. He listed them as US control of Iran’s enriched uranium, and a verification mechanism to ensure it does not develop a nuclear weapon in the future.

“It’s one thing for the Iranians to say that they’re not going to have a nuclear weapon. It’s another thing for us to put in place the mechanism to ensure that’s not going to happen,” Vance said.

He also said that in return for a two-week ceasefire agreed to by the two sides last week, Washington expects Iran to fully reopen the vital Strait of Hormuz waterway, which has been effectively closed by Tehran’s forces.