Trump threatens to strike Iran over support for Hezbollah

The negotiations opened against a backdrop of clashes in recent days between the Israeli army and Hezbollah -- a Tehran ally -- in southern Lebanon, threatening to derail the preliminary peace deal between Tehran and Washington.

"Iran must immediately stop their highly paid PROXIES in Lebanon from causing trouble," Trump posted on his Truth Social platform. "If they don’t, we’ll hit Iran very hard again, just like we did last week, only harder!!!"

Israeli airstrikes killed at least 30 people on Saturday in eastern and southern Lebanon, before a lull in the fighting that evening, when the Israeli army was ordered to halt clashes with Hezbollah.

The memorandum of understanding signed Wednesday between the United States and Iran stipulates a cessation of hostilities on all fronts, including in Lebanon.

At the outset of the talks in Switzerland on Sunday, US Vice President JD Vance said he had seen "great progress in the last just couple of days in ensuring that the ceasefire holds in Lebanon."

"We're all working towards regional peace," he said. "I actually feel great about where we are in Lebanon. There's still some additional wood to chop but we're going to keep on working at it."

Vance asserted that Trump and the United States had done more to stop the conflict in Lebanon than any other country in recent months.