The first round of talks between high-level officials from Iran and the United States in Switzerland has ended, mediators say, with the two sides agreeing on a roadmap towards a final deal to end their more than 100-day war.

Iran and the US agreed to set up communication lines to keep the vital Strait of Hormuz open and end fighting in Lebanon at the marathon talks that ended on Monday, according to mediators.

The teams, led by US Vice President JD Vance and Iranian parliament Speaker Mohammad Bagher Ghalibaf, opened talks on Sunday as part of a two-month negotiating period set out under a preliminary deal agreed last week.

Mediators Pakistan and Qatar said the negotiators reached agreement on a “roadmap towards reaching a final deal within 60 days” with technical talks to continue for the rest of the week at the Swiss resort of Burgenstock.

“Encouraging progress has been made, including the creation of a mechanism for further technical talks,” they said, detailing a contact channel set up to “avoid incidents and miscommunication” over the Strait of Hormuz.

A “deconfliction cell” between the parties and authorities in Lebanon has also been agreed to prevent fighting from erupting there again, they said.

Al Jazeera’s Osama Bin Javaid, reporting from Lucerne, Switzerland, said mediators hailed the constructive engagement, adding that the working groups formed by the negotiators are to begin work immediately.

“A lot of work still remains to be done, and it is not yet clear how these groups will be formulated, in which capacity they will work or what format any future meeting will take,” he said.

Tehran essentially had blocked the Strait of Hormuz in retaliation against the joint attacks by Israel and the US on February 28 that touched off the war.

Lebanon was pitched into the conflict as Iran-aligned Hezbollah attacked Israel in response to the US-Israeli attacks on Iran, prompting Israel to launch a wide-scale bombing campaign and ground invasion of southern Lebanon.

After a series of false starts, Washington and Tehran last week finally signed a memorandum of understanding aimed at ending the war, which included a provision to end fighting in Lebanon between Israel and Hezbollah.

But there have been repeated clashes and Israeli attacks in Lebanon since, which prompted Iran to say days after it had reopened the Strait of Hormuz that it would again close the waterway, through which about a fifth of global oil and liquefied natural gas supplies transited before the war.

“Tireless Pakistani and Qatari mediation has delivered major progress to end Lebanon War,” Iranian Foreign Minister Abbas Araghchi wrote on X after the talks in Switzerland.

“Oil and petrochem exports are waived, blockade lifted, some frozen assets released, and major reconstruction & development plan launched for Iran. 1st real test: Lebanon deconfliction cell,” he wrote.

Al Jazeera’s Resul Serdar Atas, reporting from Tehran, said Iran achieved most of what it wanted in the talks in Switzerland because it had conditions for starting the technical talks.

“They were saying that the memorandum of understanding – particularly Articles 1, 10 and 11 – had to be initiated and implemented for the technical talks to move forward,” he said, referring to the sections on ending fighting on all fronts, including Lebanon; waiving US sanctions on Iranian energy exports; and releasing frozen Iranian assets.

“So now that they have decided that technical talks in Switzerland are going to continue throughout the whole week, we see that there is progress,” he added.

Trump’s threats

The roadmap was agreed after a shaky start to the negotiations. Iran’s delegation walked out in response to US President Donald Trump’s threats on Sunday to attack Iran over its support for Hezbollah.

“Iran must immediately stop their highly paid PROXIES in Lebanon from causing trouble,” Trump wrote on social media, apparently referring to Hezbollah. “If they don’t, we’ll hit Iran very hard again, just like we did last week, only harder!!!”

Iran hit back with a warning of its own.

“They would do better to be careful with their statements; our armed forces are ready to respond to them in a different manner. No matter what they say, we are the ones who act,” Iran’s chief negotiator, Ghalibaf, said.

Israeli Prime Minister Benjamin Netanyahu, meanwhile, said Israeli troops would remain in southern Lebanon “as long as necessary” and promised that he would “not allow Iran to acquire nuclear weapons”.

By Sunday evening, there had been no reports of Israeli attacks or continued fighting as some residents of southern Lebanon cautiously returned to their homes.

The fighting between Israel and Hezbollah has repeatedly threatened to derail peace efforts.

On Friday, planned US-Iranian talks were postponed after Israel launched deadly attacks in Lebanon following the deaths of four of its soldiers in combat.

Israel’s military chief visited troops on Sunday in southern Lebanon, where he said Hezbollah was in a “very difficult position”.

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

The overall death toll from the fighting in Lebanon has surpassed 4,100 since it escalated on March 2, the Ministry of Public Health said.

‘Historic meeting’

Vance had earlier hailed “a historic meeting” in Switzerland.

Even as Trump was threatening Iran, Vance told reporters the US president had “asked us to turn over a new leaf to transform our relationship with the people of Iran”.

Flanked by US negotiators Jared Kushner and Steve Witkoff, Vance added: “The question before us now is how much more can we accomplish together?

“Can we turn over a new leaf? Can we change relations in the Middle East permanently?

“Or do we go back to doing things the old way, which is not our preference, but it’s certainly very much something that can happen.”

Lebanon aside, there has been no indication that Iran’s support for armed groups across the region, which has long drawn the ire of the US and Israel, would be addressed in the negotiations.

Speaking on Sunday, Iranian President Masoud Pezeshkian stressed that Tehran would not relinquish its right to enrich uranium although he repeated Iran’s denial that it seeks nuclear weapons.

“We can also state in writing that we have no intention of building a bomb,” he said.