WASHINGTON : US Vice President JD Vance wtook off for Switzerland on Saturday for talks with Iran on implementing a deal to end the Middle East war, saying negotiators would discuss the Islamic republic's nuclear program and the Lebanon ceasefire.

"I think we're going to hopefully make progress on the nuclear issue, make progress on the Lebanon ceasefire issue. Those are the two big things that I think we're to be focused on," Vance told reporters before departing from Joint Base Andrews, saying he could only join the talks "for a day or two."

Negotiations had been planned in Switzerland on Friday, but were postponed at the last minute as Israel carried out a wave of deadly strikes in Lebanon after four of its soldiers were killed in combat.

Following more clashes, both Israel and Hezbollah have accused the other of violating the new truce that was part of the preliminary accord signed by the US and Iran this week.

Vance said the situation in Lebanon was "actually getting better."

"It's going to be something we're just going to have to continuously manage to ensure that... Israel and Lebanon are both safe and secure," he said.

"The big problem is that you have somebody will shoot and then somebody will respond, and you kind of have a chicken and egg problem where you've just got to stop the shooting for long enough to get the ceasefire to keep hold."

US negotiators Jared Kushner and Steve Witkoff were already in Switzerland handling technical elements of the talks, Vance said earlier.