US VICE-PRESIDENT JD Vance and senior Iranian officials arrived in Switzerland today to formally launch negotiations over their fragile peace deal.

The framework was signed last week, and now US and Iranian negotiators are in a 60-day sprint to reach an agreement on technical details with massive implications for the world economy.

However, the agreement has already been stress-tested following Israel’s repeated strikes on Lebanon at the weekend and by the subsequent announcement by Iran’s military that it had closed the Strait of Hormuz — the vital waterway that transits a fifth of the world’s traded oil and natural gas.

Mr Vance first sat down for talks with Pakistani Prime Minister Shehbaz Sharif and Staff Field Marshal Asim Munir, who has served as a key intermediary between the US and Iran throughout the conflict.

“What’s up man! Good to see you,” Mr Vance said to Mr Munir after delegations from the US and Iran, as well as mediators Pakistan and Qatar, arrived at Lake Lucerne this morning.

Iran’s main focus will be the ongoing war between Israel and Lebanon, Iranian Foreign Ministry spokesman Esmail Baghaei told Iran’s state news agency today.

Iran insists that the deal’s implementation start with the cessation of all wars, including between Israel and the Lebanese militant group Hezbollah.

Mr Baghaei said the US “has been unable or unwilling” to hold Israel to the ceasefire.

Israeli armed forces chief Lieutenant General Eyal Zamir said today that the ceasefire was fragile, and that his country’s occupying forces in Lebanon must remain ready for a possible resumption of fighting with Hezbollah.

“Hezbollah has suffered a severe and significant blow,” he said, “and we are committed to remaining prepared to continue operating and prevent its rebuilding.”

Meanwhile, the US has disputed Iran’s claim that it had once again shuttered the Strait of Hormuz.

US Energy Secretary Chris Wright said today that 67 ships had passed through the Strait of Hormuz in the last 24 hours, similar to traffic before the war.

Mr Wright also told Fox News that Iran has not yet “demined” the strait’s central shipping channel, but the US has opened a separate channel to the south and has been escorting ships through it.